Motor

Abstract

A motor comprises: a rotor that has a plurality of magnets arranged along the circumferential direction; two stators that are positioned on one side and the other side of the rotor in the axial direction, the two stators having a plurality of coils arranged along the circumferential direction and facing the rotor in the axial direction; and a motor housing that accommodates the rotor and the two stators. The rotor has an impeller that is positioned radially inward of the plurality of magnets, the impeller generating an airflow flowing from one side to the other side in the axial direction. The motor housing has: a first inflow port which is positioned on a surface on one axial-direction side and into which flows a first airflow generated along the axial direction by the rotation of the impeller; a first outflow port which is positioned on a surface on the other axial-direction side and from which the first airflow flows out; a second inflow port which is positioned on a radial-direction-side surface on the one axial-direction side with respect to the rotor and into which flows a second airflow generated along the radial direction by the first airflow; and a second outflow port which is positioned on a radial-direction-side surface on the other axial-direction side with respect to the rotor and from which the second airflow flows out.

Description

motor

[0001] The present disclosure relates to a motor.

[0002] Axial flux motors have been known in the past, in which a stator having multiple coils and a rotor having multiple magnets face each other in the axial direction inside a housing. For this axial flux motor, it has been proposed to air-cool the inside of the housing by providing a cooling passage for flowing air as a coolant inside the housing (see Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2022-024534

[0004] The above-mentioned conventional techniques have room for further improvement in terms of increasing the cooling efficiency of the motor.

[0005] The present disclosure provides a technique that can improve the cooling efficiency of a motor.

[0006] According to one aspect of the embodiment, the motor includes a rotor, two stators, and a motor housing. The rotor has a plurality of magnets arranged circumferentially. The two stators are located on one axial side and the other axial side of the rotor, have a plurality of coils arranged circumferentially, and are axially opposed to the rotor. The motor housing accommodates the rotor and the two stators. The rotor is located radially inward of the magnets and has an impeller that generates an airflow that flows from one axial direction to the other. The motor housing has a first inlet, a first outlet, a second inlet, and a second outlet. The first inlet is located on one axial side surface, through which a first airflow generated in the axial direction by rotation of the impeller flows in. The first outlet is located on the other axial side surface, through which the first airflow flows out. The second inlet is located on a radially outer surface of the rotor on one axial side, through which a second airflow generated in the radial direction by the first airflow flows in. The second outlet is located on a surface on the other radial side of the rotor in the axial direction, and the second airflow flows out through the second outlet.

[0007] According to the present disclosure, it is possible to improve the cooling efficiency of the motor. Note that the effects described herein are not necessarily limited to those described herein, and any of the effects described in the present disclosure may be achieved.

[0008] FIG. 1 is a schematic perspective view of a motor according to an embodiment, as seen from the other axial side. FIG. 2 is a schematic perspective view of a motor according to an embodiment, as seen from one axial side. FIG. 3 is an exploded perspective view showing the configuration of a motor according to an embodiment. FIG. 4 is a perspective view showing the configuration of a rotor according to an embodiment. FIG. 5 is a plan view showing the configuration of a stator according to an embodiment. FIG. 6 is a cross-sectional view showing the configuration of a motor according to an embodiment. FIG. 7 is a schematic perspective view of a motor according to a first modified example of the embodiment, as seen from the other axial side. FIG. 8 is a schematic perspective view of a motor according to the first modified example of the embodiment, as seen from one axial side. FIG. 9 is a cross-sectional view showing the configuration of a motor according to the first modified example of the embodiment. FIG. 10 is a schematic perspective view of a motor according to a second modified example of the embodiment, as seen from the other axial side. FIG. 11 is a schematic perspective view of a motor according to the second modified example of the embodiment, as seen from one axial side. FIG. 12 is a cross-sectional view showing the configuration of a motor according to the second modified example of the embodiment. FIG. 13 is a schematic perspective view of a motor according to a third modified example of the embodiment, as seen from the other axial side. FIG. 14 is a schematic perspective view of a motor according to the third modified example of the embodiment, as seen from one axial side. FIG. 15 is a cross-sectional view showing the configuration of a motor according to the third modified example of the embodiment. Fig. 16 is an exploded perspective view showing the configuration of a motor according to a third modification of the embodiment. Fig. 17 is an enlarged perspective view showing the configuration of a through hole in a driver housing according to the third modification of the embodiment. Fig. 18 is an enlarged perspective view showing the configuration of a screw hole in a motor housing according to the third modification of the embodiment. Fig. 19 is an enlarged cross-sectional view showing the configuration of a motor housing according to the third modification of the embodiment. Fig. 20 is a schematic cross-sectional view showing the configuration of a motor according to a fourth modification of the embodiment. Fig. 21 is a schematic cross-sectional view showing the configuration of a motor according to a fifth modification of the embodiment. Fig. 22 is a schematic cross-sectional view showing the configuration of a motor according to a sixth modification of the embodiment.

[0009] Hereinafter, motors according to embodiments will be described in detail. Note that the present disclosure is not limited to the embodiments described below. In addition, in the drawings shown below, the same or corresponding elements are appropriately designated by the same reference numerals.

[0010] It should also be noted that the drawings are schematic and that the dimensional relationships and ratios of elements may differ from reality. The drawings may also contain parts where the dimensional relationships and ratios differ from one another.

[0011] First, the configuration of a motor 2 according to an embodiment will be described with reference to Fig. 1 to Fig. 6. Fig. 1 is a schematic perspective view of the motor 2 according to an embodiment, as seen from the other axial side. Fig. 2 is a schematic perspective view of the motor 2 according to an embodiment, as seen from one axial side.

[0012] Fig. 3 is an exploded perspective view showing the configuration of the motor 2 according to the embodiment. Fig. 4 is a perspective view showing the configuration of the rotor 3 according to the embodiment. Fig. 5 is a plan view showing the configuration of the stator 4 according to the embodiment. Fig. 6 is a cross-sectional view showing the configuration of the motor 2 according to the embodiment.

[0013] The motor 2 according to the embodiment can be mounted on an electric flying object such as a drone or an eVTOL (electronic vertical take-off and landing aircraft), and the motor 2 according to the embodiment rotates, for example, a propeller of the electric flying object.

[0014] 3 and other figures, the motor 2 according to the embodiment includes a rotor 3, two stators 4, a motor housing 5, and a shaft 6. The motor 2 according to the embodiment is an axial flux motor in which the rotor 3 and the stator 4 face each other in the axial direction inside the motor housing 5.

[0015] In this disclosure, the term "axial direction" refers to the direction along the rotation axis Ax of the motor 2. In addition, in this disclosure, the term "circumferential direction" refers to the circumferential direction of a circle centered on the rotation axis Ax of the motor 2, and the term "radial direction" refers to the radial direction of a circle centered on the rotation axis Ax of the motor 2.

[0016] The rotor 3 is rotatably supported inside the motor 2. As shown in Fig. 4, the rotor 3 has a substantially disk-shaped main body 3b, a plurality of magnets 3c (14 magnets in the figure), and an impeller 3d. The main body 3b is made of a soft magnetic material such as an electromagnetic steel plate or a silicon steel plate.

[0017] The multiple magnets 3c are aligned along the circumferential direction on the outer periphery of the main body 3b. The multiple magnets 3c are positioned, for example, at equal intervals from one another in the circumferential direction. The multiple magnets 3c are positioned, for example, so that their north and south poles are exposed from both axial surfaces of the main body 3b. Adjacent magnets 3c have different exposed magnetic poles.

[0018] The impeller 3d is located radially inward of the magnets 3c in the main body 3b. The impeller 3d generates an airflow that flows from one side to the other in the axial direction as the rotor 3 rotates inside the motor 2. Details of this airflow will be described later.

[0019] Furthermore, a shaft 6 is fixed to the main body 3b of the rotor 3 radially inward of the impeller 3d.

[0020] 5, the stator 4 has a substantially annular main body 4b, a plurality of (12 in the figure) teeth 4c, a plurality of (12 in the figure) coils 4d, and a busbar unit 4e. Note that Fig. 5 also shows a second housing 53 of the motor housing 5, which will be described later.

[0021] The teeth 4c protrude from one axial surface of the main body 4b to one side in the axial direction. The teeth 4c are arranged in a line along the circumferential direction of the main body 4b. For example, the teeth 4c are positioned so as to be equally spaced from one another in the circumferential direction.

[0022] When viewed from the axial direction, for example, the plurality of teeth 4c are positioned so as to at least partially overlap with the plurality of magnets 3c positioned on the rotor 3. The main body 4b and the plurality of teeth 4c are made of a soft magnetic material such as an electromagnetic steel plate or a silicon steel plate.

[0023] The coil 4d is formed by, for example, winding a conductive wire having a conductive core around the teeth 4c. Alternatively, the coil 4d may be configured by fitting a wound bobbin coil onto the teeth 4c.

[0024] In this manner, in the stator 4 according to the embodiment, the coils 4d are wound around the teeth 4c that protrude along the axial direction, and therefore the magnetic flux generated in the stator 4 according to the embodiment is directed in the axial direction.

[0025] In the motor 2 according to the embodiment, as shown in FIG. 3, the two stators 4 are arranged so as to sandwich the rotor 3 in the axial direction, and are arranged so that the magnetic flux generated in each stator 4 is directed toward the rotor 3.

[0026] 5, the busbar unit 4e includes a plurality of busbars 4f and a holder 4g. Each busbar 4f is electrically connected to one or more coils 4d. The holder 4g holds the plurality of busbars 4f.

[0027] The stator 4 according to the embodiment is electrically connected to a plurality of input terminals 7. The motor 2 is driven by inputting electric power to the input terminals 7 from an external power supply (not shown). The input terminals 7 protrude radially outward from a third surface 5d of the motor housing 5 (described later), for example, as shown in FIG. 1 .

[0028] The motor housing 5 accommodates the rotor 3 and the two stators 4. The motor housing 5 has, for example, a generally cylindrical shape with a hollow interior.

[0029] 1, the motor housing 5 has a first housing 52 and a second housing 53. In the motor 2 according to this embodiment, the first housing 52 and the second housing 53 are arranged to sandwich the rotor 3 and the two stators 4 in the axial direction, as shown in FIG.

[0030] 1 and 2, the motor housing 5 has a first surface 5b, a second surface 5c, and a third surface 5d. The first surface 5b is an example of a surface on one side in the axial direction, the second surface 5c is an example of a surface on the other side in the axial direction, and the third surface 5d is an example of a surface on a radial side.

[0031] The first surface 5b is a substantially circular surface located on one axial side (the lower side in the figure) of the motor housing 5. The second surface 5c is a substantially circular surface located on the other axial side (the upper side in the figure) of the motor housing 5. The third surface 5d is a curved surface located on a radial side of the motor housing 5.

[0032] 2, the first surface 5b of the motor housing 5 has a first inlet 5e. For example, a plurality of first inlets 5e are provided along the circumferential direction. For example, the first inlet 5e is positioned so as to at least partially overlap with the impeller 3d of the rotor 3 when viewed from the axial direction.

[0033] As shown in Fig. 1, the second surface 5c of the motor housing 5 has a first outlet 5f and a through hole 5j (see Fig. 3). For example, a plurality of first outlets 5f are provided along the circumferential direction. For example, the first outlets 5f are positioned so as to at least partially overlap with the impeller 3d of the rotor 3 when viewed from the axial direction.

[0034] 3, the through hole 5j is located in the center of the second surface 5c, and the shaft 6 is inserted into the through hole 5j.

[0035] The third surface 5d of the motor housing 5 has a second inlet 5g and a second outlet 5h. The second inlet 5g is located on the third surface 5d on one axial side (lower side in the figure) of the rotor 3. For example, a plurality of second inlets 5g are provided along the circumferential direction.

[0036] The second outlet 5h is located on the third surface 5d on the other axial side (upper side in the drawing) of the rotor 3. A plurality of second outlets 5h are provided, for example, along the circumferential direction.

[0037] 6, in this embodiment, a first airflow F2 generated in the axial direction by the rotation of the impeller 3d flows in through a first inlet 5e provided in the first surface 5b, and the first airflow F2 flows out through a first outlet 5f provided in the second surface 5c.

[0038] Furthermore, in this embodiment, a second airflow F3 generated in the radial direction by the first airflow F2 flows in through a second inlet 5g provided in the third surface 5d, and the second airflow F3 flows out through a second outlet 5h provided in the third surface 5d.

[0039] Thus, in the embodiment, the motor 2 is provided with an impeller 3d, a first inlet 5e, a first outlet 5f, a second inlet 5g and a second outlet 5h, so that the first airflow F2 and the second airflow F3 can flow inside the motor 2.

[0040] 6, the paths of the first airflow F2 and the second airflow F3 generated by the rotation of the impeller 3d include paths that pass near the two stators 4. This allows heat to be efficiently absorbed from the two stators 4 and dissipated to the outside of the motor 2.

[0041] Furthermore, in this embodiment, the motor 2 is provided with two types of inlets and two types of outlets, which ensures a sufficient amount of air for cooling the interior, thereby improving the cooling efficiency of the motor 2.

[0042] 6, at least one of the second inlet 5g and the second outlet 5h may be radially opposed to the teeth 4c of the stator 4. This allows the second airflow F3 to pass near the coils 4d of the stator 4, which are the main heat source.

[0043] Therefore, according to the embodiment, the cooling efficiency of the motor 2 can be further improved.

[0044] In addition, in the embodiment, at least one of the second inlet 5g and the second outlet 5h may be radially opposed to the base end 4c2 of the tooth 4c (i.e., the main body 4b side of the tooth 4c).

[0045] This allows the second airflow F3 to reach the base end portion 4c2 of the teeth 4c, thereby further improving the cooling efficiency of the motor 2.

[0046] 3 and other figures, the motor housing 5 has a protrusion 5i on the third surface 5d that protrudes radially inward. The protrusion 5i extends, for example, along the axial direction and functions as a bolt fastening portion for fastening the first housing 52 and the second housing 53 to each other.

[0047] In the embodiment, the second inlet 5g and the second outlet 5h may be adjacent to the protrusion 5i in the circumferential direction.

[0048] A portion of the air flowing in from the second inlet 5g strikes the coils 4d of the stator 4, then splits in the circumferential direction and flows between adjacent coils 4d. At this time, the air strikes the radially extending protrusions 5i from the circumferential direction, and is guided radially inward.

[0049] As a result, the airflow flowing in the radial direction hits the protrusion 5i and is then guided to the second inlet 5g adjacent in the circumferential direction. Therefore, according to this embodiment, the cooling efficiency of the motor 2 can be further improved.

[0050] In addition, in the embodiment, when viewed from the axial direction, the busbar unit 4e of the stator 4 may be positioned so that at least a portion of the busbar unit 4e does not overlap with the impeller 3d of the rotor 3. This makes it less likely that the busbar unit 4e will obstruct the first airflow F2 generated by the rotation of the impeller 3d.

[0051] Therefore, according to the embodiment, the first airflow F2 can be efficiently caused to flow inside the motor 2, and therefore the cooling efficiency of the motor 2 can be further improved.

[0052] In addition, in the embodiment, when viewed from the axial direction, at least a portion of the busbar unit 4e may be located radially inward of the impeller 3d, and the connection portion 4h (see Figure 5) between the busbar 4f and the coil 4d may face the impeller 3d in the axial direction.

[0053] As a result, the first airflow F2 generated by the rotation of the impeller 3d hits the coil 4d and part of the bus bar 4f, which are the main heat sources, and the cooling efficiency of the motor 2 can be further improved.

[0054] Furthermore, in the embodiment, when viewed from the axial direction, the first inlet 5e may be positioned so as to at least partially overlap the impeller 3d of the rotor 3. This allows the first airflow F2 generated by the rotation of the impeller 3d to flow into the motor 2 with less pressure loss.

[0055] Therefore, according to the embodiment, the amount of air for cooling the interior can be further increased, and the cooling efficiency of the motor 2 can be further improved.

[0056] In addition, in the embodiment, when viewed from the axial direction, the first outlet 5f may be positioned so as to at least partially overlap the impeller 3d of the rotor 3. This allows the first airflow F2 generated by the rotation of the impeller 3d to flow out of the interior of the motor 2 with less pressure loss.

[0057] Therefore, according to the embodiment, the amount of air for cooling the interior can be further increased, and the cooling efficiency of the motor 2 can be further improved.

[0058] In the embodiment, the main body 3b of the rotor 3 may be made of resin. This allows the motor 2 to be lighter in weight and allows the impeller 3d, which has a complex shape, to be easily formed by injection molding or the like.

[0059] <Modification 1> Next, the configuration of the motor 2 according to Modification 1 of the embodiment will be described with reference to Figs. 7 to 9. Fig. 7 is a schematic perspective view of the motor 2 according to Modification 1 of the embodiment, as seen from the other axial side. Fig. 8 is a schematic perspective view of the motor 2 according to Modification 1 of the embodiment, as seen from one axial side. Fig. 9 is a cross-sectional view showing the configuration of the motor 2 according to Modification 1 of the embodiment.

[0060] As shown in FIGS. 7 to 9, the motor 2 according to the first modification further includes a circuit board 8 and a driver housing 9 in addition to the rotor 3, two stators 4, motor housing 5, and shaft 6 described above.

[0061] The circuit board 8 has a drive circuit that drives the motor 2. The circuit board 8 is located on one axial side (the lower side in the drawing) of the motor housing 5. The circuit board 8 is located on, for example, the first surface 5b of the motor housing 5.

[0062] The driver housing 9 accommodates the circuit board 8. The driver housing 9 has, for example, a generally cylindrical shape with one axial side (the lower side in the figure) closed. The driver housing 9 is located on one axial side (the lower side in the figure) of the motor housing 5.

[0063] The driver housing 9 accommodates the circuit board 8 therein by, for example, having an opening on the other axial side in contact with the first surface 5 b of the motor housing 5 .

[0064] 7 and 8, the driver housing 9 has a first surface 9b and a second surface 9c. The first surface 9b is an example of an axial surface, and the second surface 9c is an example of a radial surface.

[0065] The first surface 9b is a substantially circular surface located on the axial side of the driver housing 9. The second surface 9c is a curved surface located on the radial side of the driver housing 9. The second surface 9c is connected to, for example, the third surface 5d of the motor housing 5.

[0066] The second surface 9c also has a third ventilation hole 9d. The third ventilation hole 9d is located on the second surface 9c radially outward of the circuit board 8 (see FIG. 9). A plurality of third ventilation holes 9d are provided, for example, along the circumferential direction.

[0067] 9 , in Modification 1, the first airflow F2 generated by the rotation of the impeller 3d flows upstream of the first inlet 5e inside the driver housing 9. The first airflow F2 upstream of the first inlet 5e flows in from, for example, the third air vent 9d of the driver housing 9, and flows radially inside the driver housing 9.

[0068] As a result, even in a configuration in which the circuit board 8 is integrated, the circuit board 8 can also be efficiently air-cooled by drawing air from the driver housing 9 into the motor housing 5. Therefore, according to the first modification, even in a configuration in which the circuit board 8 is integrated, the cooling efficiency of the motor 2 can be improved.

[0069] 7 to 9 show an example in which the circuit board 8 and the driver housing 9 are located on one axial side of the motor housing 5, but the present disclosure is not limited to such an example. For example, the circuit board 8 and the driver housing 9 may be located on the other axial side of the motor housing 5.

[0070] In this case, the first airflow F2 generated by the rotation of the impeller 3d flows downstream of the first outlet 5f inside the driver housing 9. The first airflow F2 downstream of the first outlet 5f flows, for example, radially inside the driver housing 9 and flows out from the third air vent 9d of the driver housing 9.

[0071] As a result, even in a configuration in which the circuit board 8 is integrated, the circuit board 8 can also be efficiently air-cooled by exhausting air from the motor housing 5 to the driver housing 9. Therefore, according to the first modification, even in a configuration in which the circuit board 8 is integrated, the cooling efficiency of the motor 2 can be improved.

[0072] In addition, in the first modification, the third ventilation opening 9d located on the second surface 9c may be radially opposed to the circuit board 8. This allows the first airflow F2 to reach the circuit board 8, thereby further improving the cooling efficiency of the motor 2.

[0073] <Modification 2> Next, the configuration of the motor 2 according to Modification 2 of the embodiment will be described with reference to Figs. 10 to 12. Fig. 10 is a schematic perspective view of the motor 2 according to Modification 2 of the embodiment, as seen from the other axial side. Fig. 11 is a schematic perspective view of the motor 2 according to Modification 2 of the embodiment, as seen from one axial side. Fig. 12 is a cross-sectional view showing the configuration of the motor 2 according to Modification 2 of the embodiment.

[0074] 11 and other figures, the motor 2 according to Modification 2 differs from Modification 1 in the configuration of the driver housing 9. Specifically, in Modification 2, a third vent 9d is located on the first surface 9b of the driver housing 9 in addition to the second surface 9c.

[0075] The third ventilation holes 9 d located on the first surface 9 b are provided, for example, in a plurality along the circumferential direction, and are positioned so that at least a portion of the third ventilation holes 9 d does not overlap the circuit board 8 when viewed, for example, from the axial direction.

[0076] Here, in the second modification, as in the first modification described above, as shown in FIG. 12, the first airflow F2 generated by the rotation of the impeller 3d flows inside the driver housing 9 upstream of the first inlet 5e.

[0077] The first airflow F2 upstream of the first inlet 5e flows in, for example, from a third vent 9d located on the second surface 9c, and flows radially inside the driver housing 9. Furthermore, the first airflow F2 upstream of the first inlet 5e also flows in, for example, from the third vent 9d located on the first surface 9b.

[0078] As a result, even in a configuration in which the circuit board 8 is integrated, the circuit board 8 can also be efficiently air-cooled by drawing air from the driver housing 9 into the motor housing 5. Therefore, according to the second modification, even in a configuration in which the circuit board 8 is integrated, the cooling efficiency of the motor 2 can be improved.

[0079] In addition, in the second modification, the third ventilation opening 9d located on the second surface 9c may be radially opposed to the circuit board 8. This allows the first airflow F2 to reach the circuit board 8, thereby further improving the cooling efficiency of the motor 2.

[0080] Furthermore, in the second modification, when viewed from the axial direction, the third ventilation opening 9d located on the first surface 9b may be positioned so that at least a portion of the third ventilation opening 9d does not overlap the circuit board 8. This makes it less likely that the first airflow F2 flowing inside the driver housing 9 will be obstructed by the circuit board 8.

[0081] Therefore, according to the second modification, the first airflow F2 can be efficiently caused to flow inside the driver housing 9, and the cooling efficiency of the motor 2 can be further improved.

[0082] <Modification 3> Next, the configuration of a motor 2 according to Modification 3 of the embodiment will be described with reference to Figs. 13 to 19. Fig. 13 is a schematic perspective view of the motor 2 according to Modification 3 of the embodiment, seen from the other axial side. Fig. 14 is a schematic perspective view of the motor 2 according to Modification 3 of the embodiment, seen from one axial side. Fig. 15 is a cross-sectional view showing the configuration of the motor 2 according to Modification 3 of the embodiment.

[0083] In the motor 2 according to the modified example 3, the driver housing 9 has the same configuration as that of the above-described modified example 2. That is, in the modified example 3, as in the above-described modified example 2, the first airflow F2 generated by the rotation of the impeller 3d flows inside the driver housing 9 upstream of the first inlet 5e, as shown in FIG.

[0084] As a result, even in a configuration in which the circuit board 8 is integrated, the circuit board 8 can also be efficiently air-cooled by drawing air from the driver housing 9 into the motor housing 5. Therefore, according to Modification 3, even in a configuration in which the circuit board 8 is integrated, the cooling efficiency of the motor 2 can be improved.

[0085] Fig. 16 is an exploded perspective view showing the configuration of a motor 2 according to Modification 3 of the embodiment. Fig. 17 is an enlarged perspective view showing the configuration of a through hole 9e of a driver housing 9 according to Modification 3 of the embodiment. Fig. 18 is an enlarged perspective view showing the configuration of a screw hole 5q of a motor housing 5 according to Modification 3 of the embodiment.

[0086] 16 , in the motor 2 according to the third modification, the motor housing 5 to which the stator 4 is fixed and the driver housing 9 to which the stator 4 is fixed and which houses the circuit board 8 (see FIG. 15 ) are arranged to sandwich the rotor 3 in the axial direction. The stator 4 fixed to the driver housing 9 is housed in the motor housing 5 by fixing the motor housing 5 and the driver housing 9 together.

[0087] The motor housing 5 and the driver housing 9, which sandwich the rotor 3, are fixed from the first surface 9b (see Figure 15) side by inserting and screwing multiple bolts 20 into multiple through holes 9e (see Figure 17) and multiple screw holes 5q (see Figure 18), respectively.

[0088] As shown in Fig. 17 , through hole 9e is a hole that penetrates in the axial direction slightly inside second surface 9c of driver housing 9. As shown in Fig. 18 , screw hole 5q is a screw hole that extends in the axial direction slightly inside third surface 5d of motor housing 5, and is provided at a position corresponding to through hole 9e (see Fig. 17 ). More specifically, motor housing 5 has protrusion 5i that protrudes radially inward from third surface 5d, and protrusion 5i has screw hole 5q that extends in the axial direction.

[0089] 16 , the motor housing 5 and the driver housing 9 are fixed together by inserting and screwing a plurality of bolts 20 only from the driver housing 9 side, thereby reducing the number of bolts 20 required for fixation. Therefore, according to the third modification, the weight of the motor 2 can be reduced.

[0090] In addition, in Modification 3, as shown in Fig. 17, a through hole 9e may be provided to prevent the second surface 9c from protruding outward, and a screw hole 5q may be provided to prevent the third surface 5d from protruding outward, as shown in Fig. 18. This allows the outer diameter of the motor 2 to be reduced and the outer shapes of the motor housing 5 and driver housing 9 to be simplified, making manufacturing easier.

[0091] In addition, in Modification 3, as shown in FIG. 17, the driver housing 9 may have a convex portion 9f near the through hole 9e, and as shown in FIG. 18, the motor housing 5 may have a concave portion 5r near the screw hole 5q.

[0092] In Modification 3, the motor housing 5 and the driver housing 9 may be fixed together so that the protrusions 9f fit into the recesses 5r. This allows for easy alignment of the motor housing 5 and the driver housing 9. By fixing the stator 4 using the protrusions 9f and the recesses 5r as references, the phase of the stator 4 fixed to the motor housing 5 and the stator 4 fixed to the driver housing 9 can be easily aligned.

[0093] Note that the present disclosure is not limited to using the convex portion 9f and the concave portion 5r to align the motor housing 5 and the driver housing 9. For example, holes may be formed in both the motor housing 5 and the driver housing 9, and the holes may be aligned using pins that are separate members.

[0094] This also makes it possible to easily align the motor housing 5 and the driver housing 9, thereby making it possible to easily align the phases of the stator 4 housed in the motor housing 5 and the stator 4 housed in the driver housing 9.

[0095] Fig. 19 is an enlarged cross-sectional view showing the configuration of a motor housing 5 according to Modification 3 of the embodiment. As shown in Fig. 19, Modification 3 may include a lightening portion 5s provided in the motor housing 5. When viewed from the axial direction, this lightening portion 5s is positioned so as to at least partially overlap with the screw hole 5q, and is a portion recessed outward on the inner circumferential surface of the motor housing 5.

[0096] This allows the weight of the motor housing 5 to be reduced, and therefore the weight of the motor 2 to be reduced.

[0097] In addition, in the third modification, the protrusion 5i extends from the lower side to the upper side along the axial direction to an extent that does not overlap with the rotor 3 in the radial direction. In other words, the protrusion 5i protrudes from a region on the radially inner side of the third surface 5d that does not overlap with the rotor 3 in the radial direction.

[0098] As a result, the protrusions 5i do not overlap the rotor 3 in the radial direction, and contact between the protrusions 5i and the rotor 3 can be suppressed.

[0099] <Modification 4> Next, the configuration of the motor 2 according to Modification 4 of the embodiment will be described with reference to Fig. 20. Fig. 20 is a schematic cross-sectional view showing the configuration of the motor 2 according to Modification 4 of the embodiment.

[0100] As shown in FIG. 20 , the motor 2 according to the fourth modification includes two rotors 3 , a stator 4 , a motor housing 5 , and a shaft 6 .

[0101] The rotor 3 is rotatably supported inside the motor 2. The rotor 3 has a substantially disk-shaped main body 3b, a plurality of magnets 3c, and an impeller 3d.

[0102] The multiple magnets 3c are aligned along the circumferential direction on the outer periphery of the main body 3b. The multiple magnets 3c are positioned, for example, at equal intervals from one another in the circumferential direction. The multiple magnets 3c are positioned, for example, so that the north pole or south pole is exposed from one axial side of the main body 3b. Adjacent magnets 3c have different exposed magnetic poles.

[0103] The impeller 3d is located radially inward of the magnets 3c in the main body 3b. When the rotor 3 rotates inside the motor 2, the impeller 3d generates an airflow that flows from one side to the other in the axial direction.

[0104] Furthermore, a shaft 6 is fixed to the main body 3b of the rotor 3 radially inward of the impeller 3d.

[0105] The stator 4 has a substantially disk-shaped main body 4b, multiple teeth 4c, and multiple coils 4d. The multiple teeth 4c protrude from both axially opposite surfaces of the main body 4b. The multiple teeth 4c are aligned along the circumferential direction on both sides of the main body 4b. For example, the multiple teeth 4c are positioned so as to be equally spaced from one another in the circumferential direction.

[0106] The coil 4d is formed by, for example, winding a conductive wire having a conductive core around the teeth 4c. Alternatively, the coil 4d may be configured by fitting a wound bobbin coil onto the teeth 4c.

[0107] In this way, in the stator 4 according to the fourth modification, the coil 4d is wound around the teeth 4c that protrude along the axial direction, and therefore the magnetic flux generated in the stator 4 according to the fourth modification is directed in the axial direction.

[0108] In the motor 2 according to the fourth modification, as shown in FIG. 20, the two rotors 3 are arranged so as to sandwich the stator 4 in the axial direction, and the magnetic flux generated in the stator 4 toward both sides in the axial direction is arranged to be directed toward each of the two rotors 3.

[0109] Furthermore, the main body 4b of the stator 4 has a plurality of through holes 4i. The plurality of through holes 4i are positioned so that at least a portion of each of the through holes 4i overlaps with the impeller 3d of the rotor 3 when viewed from the axial direction, for example.

[0110] The motor housing 5 accommodates the two rotors 3 and the stator 4. The motor housing 5 has, for example, a generally cylindrical shape with a hollow interior.

[0111] The motor housing 5 has a first surface 5b, a second surface 5c, and a third surface 5d. The first surface 5b is a substantially circular surface located on one axial side of the motor housing 5 (the lower side in the figure). The second surface 5c is a substantially circular surface located on the other axial side of the motor housing 5 (the upper side in the figure). The third surface 5d is a curved surface located on a radial side of the motor housing 5.

[0112] The first surface 5 b of the motor housing 5 has a fourth vent hole 5 k. For example, a plurality of the fourth vent holes 5 k are provided along the circumferential direction. For example, the fourth vent hole 5 k is positioned so as to at least partially overlap with the impeller 3 d of the rotor 3 when viewed from the axial direction.

[0113] The second surface 5 c of the motor housing 5 has a fifth vent 5 n. For example, a plurality of fifth vents 5 n are provided along the circumferential direction. For example, the fifth vent 5 n is positioned so as to at least partially overlap with the impeller 3 d of the rotor 3 when viewed from the axial direction.

[0114] The third surface 5d of the motor housing 5 has a sixth ventilation hole 5p. The sixth ventilation hole 5p is an example of a ventilation hole. For example, the sixth ventilation hole 5p is located on the third surface 5d and radially faces the teeth 4c of the stator 4. For example, a plurality of sixth ventilation holes 5p are provided along the circumferential direction.

[0115] Here, in the fourth modification, the two impellers 3d provided on each of the two rotors 3 generate airflows in the same axial direction by the rotation of the two rotors 3.

[0116] 20, in the fourth modification, the rotation of the two rotors 3 generates a third airflow F4 that flows along the axial direction inside the motor 2. For example, this third airflow F4 flows in through the fourth air vent 5k, passes through the through-hole 4i of the stator 4, and flows out through the fifth air vent 5n.

[0117] Furthermore, in the fourth modification, the third airflow F4 generates a fourth airflow F5 that flows along the radial direction. The fourth airflow F5 flows out from the sixth ventilation opening 5p, for example.

[0118] In this way, in variant example 4, two impellers 3d, a fourth air vent 5k, a fifth air vent 5n and a sixth air vent 5p are provided in the motor 2, so that a third air flow F4 and a fourth air flow F5 can be circulated inside the motor 2.

[0119] 20 , the paths of the third airflow F4 and the fourth airflow F5 generated by the rotation of the two impellers 3d include paths that pass near both surfaces of the stator 4. This allows heat to be efficiently absorbed from both surfaces of the stator 4 and dissipated to the outside of the motor 2.

[0120] Furthermore, in the fourth modification, three types of vents are provided in the motor 2, which ensures a sufficient amount of air for cooling the interior. Therefore, according to the fourth modification, the cooling efficiency of the motor 2 can be improved.

[0121] 20, in the fourth modification, the sixth ventilation hole 5p may be arranged radially opposite to the teeth 4c of the stator 4. This allows the fourth airflow F5 to pass near the coils 4d of the stator 4, which are the main heat source.

[0122] Therefore, according to the fourth modification, the cooling efficiency of the motor 2 can be further improved.

[0123] In addition, in the fourth modification, the sixth ventilation holes 5p may be arranged radially opposite the base ends of the teeth 4c (i.e., the sides of the teeth 4c facing the main bodies 4b), thereby allowing the fourth airflow F5 to reach the base ends of the teeth 4c, further improving the cooling efficiency of the motor 2.

[0124] In addition, in the fourth modification, the fourth vent hole 5k may be positioned so as to at least partially overlap the impeller 3d of the rotor 3 when viewed from the axial direction. This allows the third airflow F4 generated by the rotation of the impeller 3d to flow into the motor 2 with less pressure loss.

[0125] Therefore, according to the fourth modification, the amount of air for cooling the interior can be further increased, and the cooling efficiency of the motor 2 can be further improved.

[0126] In addition, in the fourth modification, the fifth vent hole 5n may be positioned so as to at least partially overlap the impeller 3d of the rotor 3 when viewed from the axial direction. This allows the third airflow F4 generated by the rotation of the impeller 3d to flow out of the interior of the motor 2 with less pressure loss.

[0127] Therefore, according to the fourth modification, the amount of air for cooling the interior can be further increased, and the cooling efficiency of the motor 2 can be further improved.

[0128] <Fifth Modification> Next, the configuration of the motor 2 according to a fifth modification of the embodiment will be described with reference to Fig. 21. Fig. 21 is a schematic cross-sectional view showing the configuration of the motor 2 according to the fifth modification of the embodiment.

[0129] 21 , the motor 2 according to the fifth modification differs from the motor 2 according to the fourth modification in the configuration of the two rotors 3. Specifically, in the fifth modification, the two impellers 3d provided on the two rotors 3 respectively generate airflows in opposite axial directions by the rotation of the two rotors 3.

[0130] 21 , in Modification 5, the rotation of the two rotors 3 generates two fifth airflows F6 that flow along the axial direction inside the motor 2. The fifth airflows F6 flow in through, for example, the fourth air vent 5k and the fifth air vent 5n.

[0131] Furthermore, in the fifth modification, the fifth airflow F6 generates a sixth airflow F7 that flows along the radial direction. The sixth airflow F7 flows out from the sixth ventilation opening 5p, for example.

[0132] In this way, in variant example 5, two impellers 3d, a fourth air vent 5k, a fifth air vent 5n and a sixth air vent 5p are provided in the motor 2, so that a fifth air flow F6 and a sixth air flow F7 can be circulated inside the motor 2.

[0133] 21 , the paths of the fifth airflow F6 and the sixth airflow F7 generated by the rotation of the two impellers 3d include paths that pass near both sides of the stator 4. This allows heat to be efficiently absorbed from both sides of the stator 4 and dissipated to the outside of the motor 2.

[0134] Furthermore, in the fifth modification, three types of vents are provided in the motor 2, which ensures a sufficient amount of air for cooling the interior. Therefore, according to the fifth modification, the cooling efficiency of the motor 2 can be improved.

[0135] <Sixth Modification> Next, the configuration of the motor 2 according to a sixth modification of the embodiment will be described with reference to Fig. 22. Fig. 22 is a schematic cross-sectional view showing the configuration of the motor 2 according to the sixth modification of the embodiment.

[0136] 22 , the motor 2 according to Modification 6 differs from the above-described Modifications 4 and 5 in the configuration of the two rotors 3. Specifically, in Modification 6, the two impellers 3d provided on each of the two rotors 3 generate airflows in opposite axial directions as the two rotors 3 rotate.

[0137] 22 , in the sixth modification, two seventh airflows F8 flowing along the axial direction are generated inside the motor 2 by the rotation of the two rotors 3. The seventh airflows F8 flow in through, for example, the fourth air vent 5k and the fifth air vent 5n.

[0138] Furthermore, in Modification 6, the seventh airflow F8 generates an eighth airflow F9 that flows along the radial direction. The eighth airflow F9 flows in from the sixth ventilation opening 5p, for example.

[0139] In this way, in variant example 6, two impellers 3d, a fourth air vent 5k, a fifth air vent 5n and a sixth air vent 5p are provided in the motor 2, so that a seventh air flow F8 and an eighth air flow F9 can be circulated inside the motor 2.

[0140] 22 , the paths of the seventh airflow F8 and the eighth airflow F9 generated by the rotation of the two impellers 3d include paths that pass near both sides of the stator 4. This allows heat to be efficiently absorbed from both sides of the stator 4 and dissipated to the outside of the motor 2.

[0141] Furthermore, in the sixth modification, three types of vents are provided in the motor 2, which ensures a sufficient amount of air for cooling the interior. Therefore, according to the sixth modification, the cooling efficiency of the motor 2 can be improved.

[0142] Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments, and various modifications are possible without departing from the spirit of the present disclosure.

[0143] Further advantages and modifications will readily occur to those skilled in the art. Therefore, the disclosure in its broader aspects is not limited to the specific details and representative embodiments shown and described above. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.

[0144] The present technology can be configured as follows: (1) A motor including: a rotor having a plurality of magnets arranged in a circumferential direction; two stators located on one axial side and the other axial side of the rotor, each having a plurality of coils arranged in a circumferential direction and axially facing the rotor; and a motor housing accommodating the rotor and the two stators, wherein the rotor is located radially inward of the plurality of magnets and has an impeller that generates an airflow that flows from one axial direction to the other, and the motor housing has: a first inlet located on one axial surface through which a first airflow generated in the axial direction by rotation of the impeller flows in; a first outlet located on the other axial surface through which the first airflow flows out; a second inlet located on a radial surface on one axial side of the rotor through which a second airflow generated in the radial direction by the first airflow flows in; and a second outlet located on the radial surface on the other axial side of the rotor through which the second airflow flows out. (2) The motor according to (1), wherein at least one of the second inlet and the second outlet radially faces the teeth around which the coils are wound. (3) The motor according to (2), wherein at least one of the second inlet and the second outlet radially faces the base ends of the teeth. (4) The motor according to any one of (1) to (3), wherein the motor housing has a convex portion that protrudes radially inward on a radial surface of the motor housing, and the second inlet and the second outlet are adjacent to the convex portion in the circumferential direction. (5) The motor according to (4), wherein the convex portion protrudes from a region of the radial surface of the motor housing that does not radially overlap with the rotor. (6) The motor according to any one of (1) to (5), wherein the stator has an annular busbar unit including a plurality of busbars electrically connected to the plurality of coils, respectively, and a holder that holds the plurality of busbars, and when viewed from the axial direction, the busbar unit is positioned so that at least a portion of the busbar unit does not overlap the impeller.(7) The motor according to (6), wherein at least a portion of the busbar unit is located radially inward of the impeller, and a connection portion between the busbar and the coil faces the impeller in the axial direction. (8) The motor according to any one of (1) to (7), further comprising: a circuit board having a drive circuit; and a driver housing that accommodates the circuit board, wherein the circuit board and the driver housing are located on one or the other of the axial sides of the motor housing, and the driver housing has a third vent hole on at least one of its radial side surface or its axial side surface. (9) The motor according to (8), wherein the third vent hole is located on the axial side surface of the driver housing, and is located so that at least a portion of the third vent hole does not overlap with the circuit board when viewed from the axial direction. (10) A motor comprising: two rotors each having a plurality of magnets arranged in a circumferential direction; a stator having a plurality of coils arranged in a circumferential direction and facing the two rotors in the axial direction on each of the axial sides; and a motor housing accommodating the two rotors and the stator, wherein the two rotors are located radially inward of the plurality of magnets and each have an impeller that generates an airflow that flows in the axial direction; and the motor housing is located on a radial surface between the two rotors in the axial direction and has an air vent through which the airflow generated in the radial direction flows in or out.

[0145] 2 Motor 3 Rotor 3c Magnet 3d Impeller 4 Stator 4c Teeth 4c2 Base end portion 4d Coil 4e Busbar unit 4f Busbar 4g Holder 4h Connection portion 5 Motor housing 5b First surface (an example of a surface on one side in the axial direction) 5c Second surface (an example of a surface on the other side in the axial direction) 5d Third surface (an example of a surface on the radial side) 5e First inlet 5f First outlet 5g Second inlet 5h Second outlet 5i Convex portion 5p Sixth vent (an example of a vent) 8 Circuit board 9 Driver housing 9b First surface (an example of a surface on the axial side) 9c Second surface (an example of a surface on the radial side) 9d Third vent F2 First airflow F3 Second airflow

Claims

1. A motor comprising: a rotor having a plurality of magnets arranged circumferentially; two stators located on one axial side and the other axial side of the rotor, each stator having a plurality of coils arranged circumferentially and axially facing the rotor; and a motor housing accommodating the rotor and the two stators, wherein the rotor is located radially inward of the plurality of magnets and has an impeller that generates an airflow that flows from one axial direction to the other, and the motor housing has: a first inlet located on one axial surface and through which a first airflow generated in the axial direction by the rotation of the impeller flows in; a first outlet located on the other axial surface and through which the first airflow flows out; a second inlet located on a radial surface on one axial side of the rotor and through which a second airflow generated in the radial direction by the first airflow flows in; and a second outlet located on a radial surface on the other axial side of the rotor and through which the second airflow flows out.

2. The motor according to claim 1, wherein at least one of the second inlet and the second outlet is radially opposed to the teeth around which the coil is wound.

3. The motor according to claim 2, wherein at least one of the second inlet and the second outlet is radially opposed to the base end of the tooth.

4. The motor according to claim 1, wherein the motor housing has a convex portion that protrudes radially inward on a radial surface of the motor housing, and the second inlet and the second outlet are adjacent to the convex portion in the circumferential direction.

5. The motor according to claim 4, wherein the protrusions protrude from a region on the radial surface of the motor housing that does not radially overlap with the rotor.

6. The motor according to claim 1, wherein the stator has an annular busbar unit having a plurality of busbars electrically connected to the plurality of coils, respectively, and a holder for holding the plurality of busbars, and when viewed from the axial direction, the busbar unit is positioned so that at least a portion of it does not overlap the impeller.

7. The motor according to claim 6, wherein at least a portion of the busbar unit is located radially inward of the impeller, and a connection portion between the busbar and the coil faces the impeller in the axial direction.

8. The motor according to claim 1, further comprising: a circuit board having a drive circuit; and a driver housing that houses the circuit board, wherein the circuit board and the driver housing are located on one or the other of the axial sides of the motor housing, and the driver housing has a third vent hole on at least one of its radial side surface and its axial side surface.

9. The motor according to claim 8, wherein the third ventilation hole is located on the axial side surface of the driver housing and is located so that at least a portion of the third ventilation hole does not overlap the circuit board when viewed from the axial direction.

10. A motor comprising: two rotors each having a plurality of magnets arranged circumferentially; a stator having a plurality of coils arranged circumferentially and facing the two rotors in the axial direction on each of the axial sides; and a motor housing accommodating the two rotors and the stator, wherein the two rotors are located radially inward of the plurality of magnets and each have an impeller that generates an airflow that flows in the axial direction; and the motor housing is located on the radial surface between the two rotors in the axial direction and has an air vent through which the airflow generated in the radial direction flows in and out.

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