Motor

Abstract

One embodiment of the motor according to the present invention comprises: a rotor that can rotate around the central axis; an annular stator that is positioned on one side of the rotor in the axial direction and surrounds the central axis; a housing to which the stator is fixed; and a resin portion in which at least a part of the stator is embedded. The stator has: a first core member having a plurality of tooth portions that extend in the axial direction and are disposed at intervals in the circumferential direction; and a plurality of coils respectively attached to the plurality of tooth portions. The resin portion connects the housing and the stator. The housing has a core support portion positioned on one side of the stator in the axial direction. The first core member is fixed to the core support portion by a plurality of screw members arranged at intervals around the central axis.

Description

Motor

[0001] The present invention relates to a motor. This application claims priority based on Japanese Patent Application No. 2025-015137 filed in Japan on January 31, 2025, and the content thereof is incorporated herein by reference.

[0002] Axial flux type motors are known (for example, Patent Document 1).

[0003] U.S. Patent No. 9,577,478

[0004] In the axial flux type motor as described above, the core member of the stator may be fixed to the housing by a plurality of screw members. In this case, when improving the fixing strength of the core member, for example, increasing the tightening margin of each screw member and increasing the number of screw members can be considered. However, in this case, the portion of the core member where screw holes are provided increases, and the magnetic characteristics of the motor may deteriorate.

[0005] In view of the above circumstances, one object of the present invention is to provide a motor having a structure capable of improving the fixing strength of the core member with respect to the housing while suppressing deterioration of magnetic characteristics.

[0006] One aspect of the motor of the present invention includes a rotor rotatable about a central axis, an annular stator located on one axial side of the rotor and surrounding the central axis, a housing to which the stator is fixed, and a resin portion in which at least a part of the stator is embedded. The stator includes a first core member having a plurality of teeth portions extending in the axial direction and spaced apart in the circumferential direction, and a plurality of coils respectively attached to the plurality of teeth portions. The resin portion connects the housing and the stator. The housing has a core support portion located on one axial side of the stator. The first core member is fixed to the core support portion by a plurality of screw members spaced apart around the central axis.

[0007] According to one aspect of the present invention, in a motor, it is possible to improve the fixing strength of the core member with respect to the housing while suppressing deterioration of the magnetic characteristics of the motor.

[0008] Figure 1 is a cross-sectional view showing a motor according to one embodiment. Figure 2 is a cross-sectional view showing a part of the motor according to one embodiment. Figure 3 is a perspective view showing a part of the motor according to one embodiment. Figure 4 is a perspective view showing a first core member according to one embodiment. Figure 5 is a perspective view showing the first core member according to one embodiment, viewed from a different angle than in Figure 4. Figure 6 is a view of the first core member according to one embodiment in the axial direction. Figure 7 is a cross-sectional view showing the positioning structure between the housing and the first core member according to one embodiment. Figure 8 is a cross-sectional view showing a part of the stator and a part of the rotor according to one embodiment. Figure 9 is a perspective view showing a second core member according to one embodiment. Figure 10 is a view of the second core member according to one embodiment in the axial direction.

[0009] Each figure shows the central axis J of the motor 100 in the following embodiment, as appropriate. The central axis J is a virtual axis. In the following description, the direction in which the central axis J extends, that is, the axial direction of the central axis J, will be simply called the "axial direction," the radial direction centered on the central axis J will be simply called the "radial direction," and the circumferential direction centered on the central axis J will be simply called the "circumferential direction." In each figure, the Z-axis parallel to the axial direction is shown. In the following description, the side of the axial direction in which the Z-axis arrow points (+Z side) will be called the "front side," and the side of the axial direction opposite to the side in which the Z-axis arrow points (-Z side) will be called the "rear side." Note that the front side and rear side are simply names used to describe the arrangement of each part, etc., and the actual arrangement may be other than the arrangement indicated by these names.

[0010] The motor 100 shown in Figure 1 is a motor provided in the propulsion system 1000. The propulsion system 1000 is mounted, for example, on an unmanned aerial vehicle. The propulsion system 1000 generates thrust for the unmanned aerial vehicle to move. As shown in Figure 1, the propulsion system 1000 comprises the motor 100 and a propeller 1100. The propeller 1100 is rotated around the central axis J by the motor 100. The propeller 1100 is attached to the shaft 20 of the motor 100, which will be described later. The propeller 1100 has a fixed part 1110 that is fixed to the shaft 20 and a plurality of blade parts 1120 connected to the fixed part 1110. The plurality of blade parts 1120 extend radially and are arranged with spacing in the circumferential direction.

[0011] Motor 100 is an axial flux type motor. In this embodiment, motor 100 is a double-stator type axial flux type motor having two stators 30a and 30b arranged axially on either side of the rotor 21. In this embodiment, motor 100 is a three-phase motor. Motor 100 comprises a housing 10, a shaft 20, a rotor 21, two stators 30a and 30b, two busbar assemblies 40a and 40b, and two resin parts 50a and 50b. In the following description, when stator 30a and stator 30b are not specifically distinguished, they may be collectively referred to as stator 30.

[0012] The housing 10 houses the rotor 21, two stators 30a and 30b, two busbar assemblies 40a and 40b, and two resin parts 50a and 50b. Although not shown in the figures, the housing 10 is attached to the equipment on which the motor 100 is mounted. The housing 10 is made of a non-magnetic material. In this specification, "a certain object is made of a non-magnetic material" includes the case where a certain object is made of a paramagnetic material and the case where a certain object is made of a diamagnetic material. In this embodiment, the housing 10 is made of metal. The metal constituting the housing 10 is, for example, aluminum.

[0013] In this embodiment, the housing 10 includes a first housing member 11 and a second housing member 12. The stator 30a and busbar assembly 40a are fixed to the first housing member 11. The stator 30b and busbar assembly 40b are fixed to the second housing member 12. The first housing member 11 is located on the front side (+Z side) of the second housing member 12. The first housing member 11 includes a core support portion 11a, a bearing support portion 11b, an outer wall portion 11c, and an inner wall portion 11d. In other words, the housing 10 includes a core support portion 11a, a bearing support portion 11b, an outer wall portion 11c, and an inner wall portion 11d.

[0014] The core support portion 11a is located on the front side (+Z side) of the stator 30a. In this embodiment, the core support portion 11a is plate-shaped with its plate surface facing axially. The core support portion 11a is annular in shape surrounding the central axis J. The core support portion 11a has a plurality of through holes 11e that penetrate the core support portion 11a in the axial direction. The plurality of through holes 11e are spaced apart in the circumferential direction. Although not shown in the figures, the number of the plurality of through holes 11e is, for example, eight. The number of the plurality of through holes 11e is not particularly limited as long as there are two or more. It is preferable that there are three or more of the plurality of through holes 11e. The bearing support portion 11b is connected to the radially inner edge of the core support portion 11a. The bearing support portion 11b is cylindrical in shape surrounding the central axis J. The bearing support portion 11b opens on both sides in the axial direction. The bearing support portion 11b protrudes axially on both sides from the radially inner edge of the core support portion 11a. The bearing 24a is located radially inside the bearing support portion 11b.

[0015] The outer wall portion 11c protrudes from the radial outer edge of the core support portion 11a toward the rear (-Z side). The outer wall portion 11c is located radially outward of the stator 30a. The outer wall portion 11c is an annular shape surrounding the stator 30a. The inner wall portion 11d protrudes from the core support portion 11a toward the rear. The inner wall portion 11d is located radially inward of the stator 30a. The inner wall portion 11d is an annular shape surrounding the central axis J. The inner wall portion 11d is located radially inward and separated from the outer wall portion 11c. The rear end of the inner wall portion 11d is located further forward (+Z side) than the rear end of the outer wall portion 11c.

[0016] The first housing member 11 has a plurality of fins 13. The plurality of fins 13 protrude radially outward from the outer wall portion 11c. The plurality of fins 13 are plate-shaped with their plate surfaces facing the circumferential direction. As shown in Figures 2 and 3, the plurality of fins 13 are arranged with spacing in the circumferential direction. The number of plurality of fins 13 is not particularly limited, as long as there are two or more.

[0017] The second housing member 12 has the same configuration as the first housing member 11 described above, except that the stator 30 to which it is fixed is different and is reversed in the axial direction. Although not shown in the figures, the second housing member 12 is attached to the equipment on which the motor 100 is mounted. As shown in Figure 1, the second housing member 12 has a core support portion 11f, a bearing support portion 11g, an outer wall portion 11h, and an inner wall portion 11i. In other words, the housing 10 has a core support portion 11f, a bearing support portion 11g, an outer wall portion 11h, and an inner wall portion 11i. The core support portion 11f is located on the rear side (-Z side) of the stator 30b. The bearing 24b is located radially inward of the bearing support portion 11g. The front end (+Z side) of the outer wall portion 11h is fixed to the rear end of the outer wall portion 11c.

[0018] The shaft 20 extends in the axial direction. The shaft 20 is, for example, substantially cylindrical with a central axis J. The shaft 20 passes axially through the radially inward side of the bearing support portion 11b and the radially inward side of the bearing support portion 11g. The propeller 1100 is attached to the front end (+Z side) of the shaft 20.

[0019] The shaft 20 is rotatably supported around the central axis J by two bearings 24a and 24b. The two bearings 24a and 24b are rolling bearings, such as ball bearings. Each bearing 24a and 24b is fitted radially inward to each bearing support portion 11b and 11g. A contact member 26a is attached to the shaft 20, which contacts the front (+Z side) surface of the inner ring of bearing 24a. The outer ring of bearing 24a is supported from the rear (-Z side) by a support member 25a fixed radially inward to bearing support portion 11b. The preload applied to bearing 24a is adjusted by adjusting the axial position of the contact member 26a. A contact member 26b is attached to the shaft 20, which contacts the rear surface of the inner ring of bearing 24b. The outer ring of bearing 24b is supported from the front by a support member 25b fixed radially inward to bearing support portion 11b. The preload applied to the bearing 24b is adjusted by adjusting the axial position of the contact member 26b.

[0020] The rotor 21 is fixed to the shaft 20. The rotor 21 is rotatable about a central axis J. The rotor 21 has a rotor core 22 and a plurality of magnets 23. The rotor core 22 is located radially outward from the shaft 20. The rotor core 22 is annular and surrounds the shaft 20. The rotor core 22 is fixed to the outer circumferential surface of the shaft 20. The rotor core 22 has a plurality of holes 22a that penetrate the rotor core 22 in the axial direction. The plurality of holes 22a are spaced apart in the circumferential direction. The plurality of magnets 23 are each placed inside the plurality of holes 22a. The plurality of magnets 23 are fixed to the rotor core 22. The magnetization direction of the plurality of magnets 23 is axial. Each of the magnets 23 may consist of a single magnet or may be composed of a combination of multiple magnets.

[0021] The two stators 30a and 30b are fixed to the housing 10. The two stators 30a and 30b form an annular shape surrounding the central axis J. The two stators 30a and 30b are positioned to sandwich the rotor 21 in the axial direction. Stator 30a is located on the front side (+Z side) of the rotor 21. Stator 30b is located on the rear side (-Z side) of the rotor 21. Stator 30b has the same configuration as stator 30a, except that it sandwiches the rotor 21 in the axial direction and is reversed in the axial direction. Therefore, in the following description, stator 30a will be described as a representative of the two stators 30a and 30b, and the description of stator 30b may be omitted.

[0022] The stator 30a is located radially between the outer wall portion 11c and the inner wall portion 11d. The stator 30a includes a first core member 31, a plurality of second core members 32, a plurality of insulators 33, and a plurality of coils 34. As shown in Figures 4, 5, and 6, the first core member 31 is annular in shape surrounding the central axis J. In this embodiment, the first core member 31 is an annular shape centered on the central axis J when viewed in the axial direction. The first core member 31 is made of a magnetic material. In this specification, "a certain object is made of a magnetic material" includes "a certain object is made of a ferromagnetic material." The first core member 31 is, for example, a spiral core composed of plate members extending in a spiral shape around the central axis J. The plate members are, for example, electrical steel sheets. The first core member 31 may be composed of a plurality of plate members, such as electrical steel sheets, stacked radially. As shown in Figures 4 and 5, the first core member 31 has a base portion 31a and a plurality of teeth portions 35.

[0023] The base portion 31a is annular in shape surrounding the central axis J. In this embodiment, the base portion 31a is an annular shape centered on the central axis J when viewed in the axial direction. As shown in Figure 4, the base portion 31a has a plurality of recesses 31b that are recessed from the front side (+Z side) to the rear side (-Z side). In this embodiment, the plurality of recesses 31b are grooves that extend in the radial direction. Each recess 31b extends radially from the radial inner edge to the radial outer edge of the base portion 31a. The interior of each recess 31b opens on both radial sides. In this embodiment, the circumferential dimensions of each recess 31b are the same throughout the radial direction. The bottom surface of each recess 31b is a substantially V-shape that is convex towards the rear when viewed in the radial direction. The plurality of recesses 31b are arranged at equal intervals along the circumference. The number of the plurality of recesses 31b is the same as the number of the plurality of teeth portions 35. In this embodiment, the number of the plurality of recesses 31b is 36. The multiple recesses 31b overlap with the multiple teeth portions 35 when viewed in the axial direction. Magnetic flux is relatively difficult to flow through the front (+Z side) portion of the base portion 31a that overlaps with each of the teeth portions 35 in the axial direction. Therefore, by providing the multiple recesses 31b that are recessed from the front surface of the base portion 31a toward the rear, at positions that overlap with the multiple teeth portions 35 when viewed in the axial direction, the obstruction of the flow of magnetic flux within the first core member 31 can be suppressed while reducing the weight of the first core member 31.

[0024] The front (+Z side) surface of the base portion 31a is divided circumferentially into multiple contact surfaces 31c by multiple recesses 31b. The multiple contact surfaces 31c are spaced apart in the circumferential direction. In this embodiment, the multiple contact surfaces 31c are spaced equally along the circumference. The number of contact surfaces 31c is the same as the number of teeth portions 35. In this embodiment, there are 36 contact surfaces 31c. In this embodiment, each contact surface 31c is a surface perpendicular to the axial direction. The circumferential dimension of each contact surface 31c increases towards the radially outward direction. In this embodiment, each contact surface 31c is trapezoidal when viewed in the axial direction. As shown in Figure 1, each contact surface 31c contacts the rear (-Z side) surface of the core support portion 11a.

[0025] As shown in Figure 4, the base portion 31a has a plurality of screw holes 36. The plurality of screw holes 36 are spaced apart in the circumferential direction. The plurality of screw holes 36 are arranged at approximately equal intervals along the circumference. The plurality of screw holes 36 are arranged surrounding the central axis J. The number of screw holes 36 is less than the number of teeth portions 35. In this embodiment, the number of plurality of screw holes 36 is 8. The number of plurality of screw holes 36 is not particularly limited as long as there are 2 or more. It is preferable that the number of plurality of screw holes 36 be 3 or more. Each of the plurality of screw holes 36 is recessed from the front side (+Z side) to the rear side (-Z side) of different contact surfaces 31c. As shown in Figure 1, a plurality of screw members 60a are screwed into each of the plurality of screw holes 36. Each screw member 60a is passed through each through hole 11e of the core support portion 11a from the front side and screwed into each screw hole 36. As a result, the first core member 31 is fixed to the core support portion 11a by a plurality of screw members 60a arranged at intervals around the central axis J. As shown in Figure 6, in this embodiment, the plurality of screw members 60a are arranged at approximately equal intervals around the circumference. The plurality of screw members 60a are arranged surrounding the central axis J. The plurality of screw members 60a are bolts. In this embodiment, the number of plurality of screw members 60a is eight. The number of plurality of screw members 60a is not particularly limited as long as there are two or more. It is preferable that the number of plurality of screw members 60a be three or more. As shown in Figure 1, a washer 61 is placed between the head of each screw member 60a and the front surface of the core support portion 11a, surrounding each screw member 60a. The washer 61 is in contact with the head of each screw member 60a and the front surface of the core support portion 11a.

[0026] As shown in Figure 4, the multiple screw holes 36 are positioned at circumferential locations different from the multiple teeth portions 35 when viewed in the axial direction. Therefore, even if the depth of the multiple screw holes 36 is increased, no part of the multiple screw holes 36 is provided in the teeth portions 35. As a result, the multiple teeth portions 35 are not worn down by the screw holes 36, and a decrease in the amount of magnetic flux flowing through the multiple teeth portions 35 can be suppressed. Therefore, even if multiple screw holes 36 are provided in the first core member 31, a decrease in the magnetic characteristics of the motor 100 can be suppressed. Furthermore, each screw hole 36 can be a hole that penetrates the base portion 31a without any part of each screw hole 36 being provided in the teeth portion 35. In this embodiment, each screw hole 36 is a hole that penetrates the base portion 31a in the axial direction. Therefore, even if the axial dimensions of the multiple screw members 60a become larger due to errors, the axial ends of the screw members 60a will not abut against the first core member 31, and the screw members 60a can be tightened firmly. The multiple screw holes 36 are positioned so as not to overlap with the multiple teeth portions 35 when viewed in the axial direction. Each screw hole 36 is located between adjacent teeth portions 35 in the circumferential direction when viewed in the axial direction.

[0027] As shown in Figure 6, the multiple screw holes 36 are positioned radially inward from the radial outer edge of the base 31a, and radially outward from the radial inner edge of the base 31a. Therefore, the multiple screw holes 36 can be positioned at the radial center C1 between the radial outer edge and the radial inner edge of the base 31a, or close to the center C1. By positioning the multiple screw holes 36 at the radial center C1 between the radial outer edge and the radial inner edge of the base 31a, or close to the center C1, the deterioration of the magnetic characteristics of the motor 100 can be suppressed compared to when the multiple screw holes 36 are positioned on the radial outer edge or the radial inner edge of the base 31a. This is a new finding obtained by the inventors through simulations. In Figure 6, the radial center C1 between the radial outer edge and the radial inner edge of the base 31a is shown by a dashed circle centered on the central axis J.

[0028] In this embodiment, the multiple screw holes 36 are located radially outward from the radial center C1 between the radial outer edge and the radial inner edge of the base portion 31a. In order to suppress the deterioration of the magnetic characteristics of the motor 100, it is preferable to position the radial position of each screw hole 36 at the radial center C1 of the base portion 31a. However, due to constraints on the position where the screw member 60a can be placed, it may not be possible to position the radial position of each screw hole 36 at the radial center C1 of the base portion 31a. In this case, by positioning each screw hole 36 radially outward from the radial center C1 of the base portion 31a, each screw hole 36 can be placed in the radially outward portion of the base portion 31a where the circumferential dimension is larger. Therefore, it is easier to provide each screw hole 36 in relation to the base portion 31a. In particular, as in this embodiment, when the circumferential dimension of the contact surface 31c where the screw holes 36 are provided increases with respect to the radially outward direction, each screw hole 36 can be provided in the portion of the contact surface 31c that has a larger circumferential dimension by arranging each screw hole 36 radially outward from the radial center C1 of the base portion 31a.

[0029] In this embodiment, the multiple screw holes 36 are located radially inward from the radial center C1 between the radial outer edge and the radial inner edge of the base 31a, and from the radial center C2 between the radial outer edge of the base 31a. Therefore, each screw hole 36 can be positioned radially outward from the center C1, while still being close to the center C1. This suppresses a decrease in the magnetic characteristics of the motor 100. In Figure 6, the center C2 is indicated by a dashed circle centered on the central axis J. In this embodiment, the radial positions of the multiple screw holes 36 are the same. The radial positions of the multiple screw holes 36 may be different.

[0030] The base portion 31a has a first positioning hole 37. As shown in Figure 7, the first positioning hole 37 is recessed from the front side (+Z side) of the base portion 31a toward the rear side (-Z side). In this embodiment, the first positioning hole 37 is a hole with a bottom on the rear side. The first positioning hole 37 is axially opposite to the second positioning hole 11j, which is recessed from the rear side of the core support portion 11a toward the front side. An axially extending positioning pin 51 is inserted into the first positioning hole 37. The positioning pin 51 is positioned across the interior of the first positioning hole 37 and the interior of the second positioning hole 11j. The positioning pin 51 is, for example, press-fitted into the interior of the first positioning hole 37 and the interior of the second positioning hole 11j. The positioning pin 51 may also be fitted into the interior of the first positioning hole 37 and the interior of the second positioning hole 11j. The positioning pin 51 is inserted into the first positioning hole 37 and the second positioning hole 11j, thereby positioning the first core member 31 circumferentially relative to the housing 10. The portion 11k of the core support portion 11a that overlaps with the second positioning hole 11j in the axial direction protrudes toward the front. As shown in Figure 6, in this embodiment, two first positioning holes 37 are provided, flanking the central axis J in the radial direction. Although not shown, two second positioning holes 11j and two positioning pins 51 are also provided, flanking the central axis J in the radial direction.

[0031] As shown in Figure 5, the multiple tooth portions 35 extend in the axial direction. The multiple tooth portions 35 extend from the base portion 31a toward the rear side (-Z side). The multiple tooth portions 35 are arranged at intervals in the circumferential direction. The multiple tooth portions 35 are arranged at equal intervals along the circumference. In this embodiment, the number of multiple tooth portions 35 is 36. As shown in Figure 1, the rear end face of each tooth portion 35 faces the rotor 21 in the axial direction with a gap between them. The rear end face of each tooth portion 35 faces the front side (+Z side) of at least one magnet 23 in the axial direction with a gap between them.

[0032] As shown in Figure 5, each tooth portion 35 has a first portion 35a and a second portion 35b. The first portion 35a extends from the base portion 31a toward the rear side (-Z side). As shown in Figure 2, the first portion 35a is substantially trapezoidal in shape, with the circumferential dimension increasing towards the radially outward direction when viewed in the axial direction, and the two radially outward corners of the substantially trapezoidal shape are chamfered. The outer circumferential surface of the first portion 35a, when viewed in the axial direction, has a pair of connecting surfaces 35c and 35d. The connecting surface 35c connects one circumferential surface of the first portion 35a to the radially outward surface of the first portion 35a. The connecting surface 35d connects the other circumferential surface of the first portion 35a to the radially outward surface of the first portion 35a. The pair of connecting surfaces 35c and 35d approach each other circumferentially as they move radially outward.

[0033] As shown in Figure 5, the second portion 35b connects to the rear (-Z side) end of the first portion 35a. The second portion 35b is the portion that includes the rear end of the teeth portion 35. The circumferential dimension of the second portion 35b is smaller than the circumferential dimension of the first portion 35a. One circumferential surface of the second portion 35b is located on the other circumferential side of the circumferential surface of the first portion 35a. The other circumferential surface of the second portion 35b is located on one circumferential side of the circumferential surface of the first portion 35a. The radial dimension of the second portion 35b is the same as the radial dimension of the first portion 35a. The second portion 35b is a substantially trapezoidal shape, with the circumferential dimension increasing towards the radially outward direction when viewed in the axial direction, and the two radially outward corners of the substantially trapezoidal shape are chamfered. As shown in Figure 3, the outer circumferential surface of the second portion 35b, when viewed in the axial direction, has a pair of connecting surfaces 35e and 35f. The connecting surface 35e connects one circumferential surface of the second portion 35b to the radially outer surface of the second portion 35b. The connecting surface 35f connects the other circumferential surface of the second portion 35b to the radially outer surface of the second portion 35b. The pair of connecting surfaces 35e and 35f approach each other in the circumferential direction as they extend radially outward.

[0034] As shown in Figure 2, multiple insulators 33 are attached to each of the multiple tooth portions 35. Each insulator 33 is cylindrical in shape and surrounds each tooth portion 35 when viewed in the axial direction. In this embodiment, each insulator 33 surrounds each first portion 35a of each tooth portion 35. As shown in Figure 1, each tooth portion 35 passes through the inside of each insulator 33 in the axial direction. As shown in Figure 8, the rear end (-Z side) of each insulator 33 is located on the front side (+Z side) than the rear end of each tooth portion 35. In this embodiment, the rear end of each insulator 33 is positioned in the same axial position as the rear end of the first portion 35a of each tooth portion 35. The rear end of each insulator 33 may be positioned axially offset from the rear end of the first portion 35a of each tooth portion 35. Each insulator 33 has insulating properties. In this embodiment, each insulator 33 is made of resin.

[0035] As shown in Figure 2, multiple coils 34 are attached to multiple tooth sections 35. In this embodiment, each coil 34 is attached to each tooth section 35 via each insulator 33. Each coil 34 surrounds each insulator 33 and each tooth section 35.

[0036] The multiple second core members 32 are separate from the first core member 31. The multiple second core members 32 are made of magnetic material. The material constituting the multiple second core members 32 is, for example, soft magnetic composite material (SMC). As shown in Figure 3, the multiple second core members 32 are annular in shape, each surrounding the rear (-Z side) end of the multiple tooth portions 35. In this embodiment, the multiple second core members 32 each surround the second portion 35b of the multiple tooth portions 35. The inner circumferential surface of each second core member 32 contacts the outer circumferential surface of each tooth portion 35. In this embodiment, the inner circumferential surface of each second core member 32 contacts the outer circumferential surface of each second portion 35b. As shown in Figure 8, the rear end face of each second core member 32 faces the rotor 21 in the axial direction with a gap between them. The rear end face of each second core member 32 faces the front (+Z) face of at least one magnet 23 in the axial direction, with a gap in between.

[0037] As shown in Figures 9 and 10, in this embodiment, the outer circumferential surface of each second core member 32 is a roughly trapezoidal shape with rounded corners, where the circumferential dimension increases as it moves radially outward when viewed in the axial direction. As shown in Figure 8, the outer circumferential surface of each second core member 32 has an inclined surface 32a that approaches each tooth portion 35 in a direction perpendicular to the axial direction as it moves toward the rear side (-Z side). In this embodiment, the inclined surface 32a is the rear portion of the outer circumferential surface of the second core member 32. In this embodiment, the inclined surface 32a of each second core member 32 is an annular shape surrounding each tooth portion 35. More specifically, the inclined surface 32a is an annular shape surrounding the second portion 35b. The inclined surface 32a has a portion facing one side in the circumferential direction, a portion facing the other side in the circumferential direction, a portion facing radially inward, and a portion facing radially outward. The portion of the inclined surface 32a facing one side in the circumferential direction and the portion of the inclined surface 32a facing the other side in the circumferential direction approach the teeth portion 35 in the circumferential direction as it moves toward the rear. The portion of the inclined surface 32a facing radially inward and the portion of the inclined surface 32a facing radially outward approach the teeth portion 35 in the radial direction as it moves toward the rear. As a result of the provision of the inclined surface 32a, the rear portion of the second core member 32 has smaller circumferential and radial dimensions as it moves toward the rear.

[0038] As shown in Figures 9 and 10, in this embodiment, the inner circumferential surface of each second core member 32 is substantially trapezoidal in shape, with the circumferential dimension increasing towards the radially outward direction when viewed in the axial direction. The inner circumferential surface of each second core member 32 has a pair of first sides 32b, 32c, a second side 32d, a pair of third sides 32e, 32f, a fourth side 32g, and a plurality of concave surfaces 32h, 32i, 32j, 32k, 32m, 32n.

[0039] The pair of first sides 32b and 32c are portions of the inner circumferential surface of the second core member 32, located on both sides in the circumferential direction. Each of the pair of first sides 32b and 32c faces the side where the other of the pair of first sides 32b and 32c is located in the circumferential direction. The pair of first sides 32b and 32c move circumferentially away from each other as they extend radially outward. The second side 32d is a portion of the inner circumferential surface of the second core member 32, located radially outward. The second side 32d faces radially inward. The pair of third sides 32e and 32f are portions of the inner circumferential surface of the second core member 32, located axially between each of the pair of first sides 32b and 32c and the second side 32d. The pair of third sides 32e and 32f move circumferentially closer to each other as they extend radially outward. Therefore, the shape of the teeth portion 35 located inside the second core member 32, when viewed in the axial direction, can be made into a roughly trapezoidal shape with two radially outer corners beveled. This suppresses the expansion of each coil 34 radially outward when winding each coil 34 around each teeth portion 35, compared to the case where the shape of the teeth portion 35 when viewed in the axial direction is a roughly trapezoidal shape with two radially outer corners not beveled. Therefore, it is possible to suppress the radial enlargement of the stator 30a. As shown in Figure 10, the third side surface 32e faces the connection surface 35e. The third side surface 32e is in contact with the connection surface 35e. The third side surface 32f faces the connection surface 35f. The third side surface 32f is in contact with the connection surface 35f. Each of the pair of third side surfaces 32e and 32f faces radially inward, on the side where the other of the pair of third side surfaces 32e and 32f is located in the circumferential direction. The fourth side surface 32g is the portion of the inner circumferential surface of the second core member 32 that is located radially inward. The fourth side surface 32g faces radially outward.

[0040] Multiple concave surfaces 32h, 32i, 32j, 32k, 32m, and 32n are recessed in an axial direction toward the outer circumferential surface of the second core member 32. The concave surface 32h connects the second side surface 32d and the third side surface 32e. The concave surface 32i connects the first side surface 32b and the third side surface 32e. The concave surface 32j connects the second side surface 32d and the third side surface 32f. The concave surface 32k connects the first side surface 32c and the third side surface 32f. The concave surface 32m connects the first side surface 32b and the fourth side surface 32g. The concave surface 32n connects the first side surface 32c and the fourth side surface 32g. Each concave surface 32h, 32i, 32j, 32k, 32m, and 32n faces each corner of the second portion 35b. The provision of the concave surfaces 32h, 32i, 32j, 32k, 32m, and 32n prevents the corners of the second portion 35b from catching on the inner circumferential surface of the second core member 32 when the second portion 35b is inserted into the inside of the second core member 32.

[0041] The first core member of the stator 30b is fixed to the core support portion 11f of the second housing member 12 by a plurality of screw members 60b, similar to the first core member 31 of the stator 30a, except that it is inverted in the axial direction. The plurality of screw members 60b overlap with the plurality of screw members 60a when viewed in the axial direction. In other words, in this embodiment, the plurality of screw members 60a that fix one stator 30a to the housing 10 and the plurality of screw members 60b that fix the other stator 30b to the housing 10 overlap when viewed in the axial direction. Therefore, compared to the case where the plurality of screw members 60a and the plurality of screw members 60b are arranged offset from each other in the circumferential direction, it is easier to balance the circumferential amount of magnetic flux flowing through each stator 30a, 30b in the circumferential direction. This makes it possible to suppress the imbalance of the circumferential magnetic characteristics of the motor 100. Furthermore, the multiple screw members 60a that fix one stator 30a to the housing 10 and the multiple screw members 60b that fix the other stator 30b to the housing 10 may be arranged offset from each other in the circumferential direction.

[0042] As shown in Figure 1, the busbar assembly 40a is located radially inward of the inner wall portion 11d. The busbar assembly 40a is located radially between the inner wall portion 11d and the bearing support portion 11b. In this embodiment, the busbar assembly 40a is annular in shape surrounding the central axis J. The busbar assembly 40a has a plurality of busbars 41 and a busbar holder 42. The plurality of busbars 41 are made of metal. As shown in Figure 3, each busbar 41 is electrically connected to a lead wire drawn from the coil 34. Although not shown, the plurality of busbars 41 are connected to an external power supply. A portion of each busbar 41 is embedded in the busbar holder 42. In this way, the plurality of busbars 41 are held in the busbar holder 42. The busbar holder 42 is made of resin.

[0043] As shown in Figure 1, the busbar assembly 40b is located radially inward of the inner wall portion 11i. The busbar assembly 40b is located radially between the inner wall portion 11i and the bearing support portion 11g. The busbar assembly 40b is annular in shape surrounding the central axis J. The busbar assembly 40b, like the busbar assembly 40a, has a plurality of busbars and a busbar holder. The busbars of the busbar assembly 40b are electrically connected to the coils of the stator 30b. The busbars of the busbar assembly 40b are connected to an external power supply. The other configurations of the busbar assembly 40b are the same as those of the busbar assembly 40a, except that they are reversed in the axial direction.

[0044] At least a part of the stator 30a is embedded in the resin portion 50a. The resin portion 50a connects the housing 10 and the stator 30a. Therefore, the stator 30a can be fixed to the housing 10 by the resin portion 50a. Thus, in the present embodiment, the stator 30a can be fixed to the housing 10 by the resin portion 50a and the plurality of screw members 60a. Therefore, even if the fixing strength of the stator 30a by the plurality of screw members 60a is reduced compared to the case where the resin portion 50a is not provided, it is easy to sufficiently ensure the fixing strength of the stator 30a with respect to the housing 10. As a result, it is easy to reduce the number of the plurality of screw members 60a, and it is also easy to shorten the tightening margin length of each screw member 60a. Therefore, the portion of the first core member 31 where the plurality of screw holes 36 are provided can be reduced. Therefore, it is possible to suppress the magnetic flux from flowing hardly through the first core member 31 due to the plurality of screw holes 36, and it is possible to suppress the deterioration of the magnetic characteristics of the motor 100. Therefore, according to the present embodiment, it is possible to improve the fixing strength of the first core member 31 with respect to the housing 10 while suppressing the deterioration of the magnetic characteristics of the motor 100. Further, the heat of the stator 30a can be transmitted to the housing 10 through the resin portion 50a. Therefore, the heat dissipation of the stator 30a can be improved. In the present embodiment, the heat transmitted from the stator 30a to the housing 10 is released from the plurality of fins 13 provided on the outer wall portion 11c to the air outside the motor 100. Further, by arranging each of the plurality of screw members 60a and the plurality of screw holes 36 at equal intervals or substantially equal intervals over one circumference in the circumferential direction, it is possible to suppress the deterioration of the balance in the circumferential direction of the magnetic flux flowing through the first core member 31. As a result, it is easy to reduce the vibration generated in the motor 100, and it is possible to suppress the generation of noise from the motor 100.

[0045] In this embodiment, the resin portion 50a connects the first housing member 11 and the stator 30a. In this embodiment, the entire stator 30a, excluding the rear end faces of each tooth portion 35 and each second core member 32, is embedded in the resin portion 50a. The rear end faces of each tooth portion 35 and each second core member 32 are exposed from the resin portion 50a. The resin portion 50a has a portion that fills the radial space between the outer wall portion 11c and the inner wall portion 11d. Therefore, the resin portion 50a can more stably fix the stator 30a radially between the outer wall portion 11c and the inner wall portion 11d. This improves the fixing strength of the first core member 31 to the housing 10. In addition, heat generated in the stator 30a can be more easily transferred to the resin portion 50a, improving the heat dissipation of the stator 30a.

[0046] As shown in Figure 8, the resin portion 50a contacts at least a portion of the inclined surface 32a of each second core member 32. As a result, a portion of the resin portion 50a catches on the inclined surface 32a from the rear side (-Z side). This prevents each second core member 32 from moving toward the rotor 21 even when it is subjected to magnetic force pulling toward the rear from the multiple magnets 23 of the rotor 21. Therefore, it is possible to prevent each second core member 32 from detaching from each tooth portion 35.

[0047] In this embodiment, the resin portion 50a contacts the inclined surface 32a of each second core member 32 over the entire circumference surrounding the inclined surface 32a. Therefore, each second core member 32 can be supported from the rear side (-Z side) by a part of the resin portion 50a over the entire circumference surrounding each second core member 32. As a result, each second core member 32 can be supported more stably from the rear side by the resin portion 50a, and the detachment of each second core member 32 from each tooth portion 35 can be further suppressed. In addition, localized stress can be suppressed on a part of each second core member 32 in the direction surrounding each tooth portion 35, and damage to each second core member 32 can be suppressed. In this embodiment, the resin portion 50a contacts the entire inclined surface 32a.

[0048] As shown in FIG. 1, the resin portion 50a has a portion located on the rear side (-Z side) of the bus bar assembly 40a. Therefore, the bus bar assembly 40a can be fixed to the housing 10 by the resin portion 50a. In the present embodiment, the resin portion 50a is annular and surrounds the central axis J. The radially inner edge portion of the resin portion 50a is located radially outside the radially inner edge portion of the bus bar assembly 40a. The radially inner edge portion of the bus bar assembly 40a is the radially inner edge portion of the bus bar holder 42.

[0049] The resin portion 50a is formed, for example, by assembling a jig to the first housing member 11 in a state where the stator 30a and the bus bar assembly 40a are assembled, and pouring resin into the interior surrounded by the jig, the outer wall portion 11c, the core support portion 11a, and the bus bar assembly 40a. The resin constituting the resin portion 50a is, for example, an epoxy resin.

[0050] At least a part of the stator 30b is embedded in the resin portion 50b. The resin portion 50b connects the housing 10 and the stator 30b. In the present embodiment, the resin portion 50b connects the second housing member 12 and the stator 30b. The resin portion 50b is provided with respect to the second housing member 12, the stator 30b, and the bus bar assembly 40b, and is the same as the resin portion 50a except that it is inverted in the axial direction.

[0051] In the present embodiment, in the positional relationship among the first housing member 11, the stator 30a, the bus bar assembly 40a, the resin portion 50a, and the rotor 21, the front side (+Z side) corresponds to "one side in the axial direction", and the rear side (-Z side) corresponds to "the other side in the axial direction". In the present embodiment, in the positional relationship among the second housing member 12, the stator 30b, the bus bar assembly 40b, the resin portion 50b, and the rotor 21, the front side (+Z side) corresponds to "the other side in the axial direction", and the rear side (-Z side) corresponds to "one side in the axial direction".

[0052] The present invention is not limited to the embodiments described above, and other configurations and methods may be adopted within the scope of the technical idea of ​​the present invention. The resin part may have any configuration as long as at least a portion of the stator is embedded in it and the housing and the stator are connected. The number of screw members is not particularly limited as long as there are two or more. The circumferential positions of the screw members and the screw holes into which the screw members are fastened are not particularly limited. The screw holes may be holes having a bottom on the other axial side. The entire outer surface of each second core member may be an inclined surface that approaches each tooth portion in a direction perpendicular to the axial direction as it moves toward the other axial side. Only a portion of the inclined surface of each second core member may be in contact with the resin part. The outer surface of each second core member does not have to be an inclined surface. The stator does not have to have a second core member. The motor according to this disclosure may be an axial flux type motor comprising one rotor and one stator. The applications of the motor according to this disclosure and the propulsion device are not particularly limited. The motor according to this disclosure may be provided in equipment other than propulsion devices.

[0053] Furthermore, this technology can take the following configuration: (1) A motor comprising a rotor rotatable about a central axis, an annular stator located on one axial side of the rotor and surrounding the central axis, a housing to which the stator is fixed, and a resin part in which at least a part of the stator is embedded, wherein the stator has a first core member having a plurality of teeth extending in the axial direction and spaced apart in the circumferential direction, and a plurality of coils attached to each of the plurality of teeth, the resin part connects the housing and the stator, the housing has a core support part located on one axial side of the stator, and the first core member is fixed to the core support part by a plurality of screw members spaced apart about the central axis. (2) The motor according to (1), wherein the housing has an annular outer wall portion located radially outside the stator and surrounding the stator, and an annular inner wall portion located radially inside the stator and surrounding the central axis, and the resin portion has a portion filled in the radial space between the outer wall portion and the inner wall portion. (3) The motor according to (1) or (2), wherein the first core member has a base, the plurality of teeth portions extend from the base to the other axial side, the base has a plurality of screw holes into which the plurality of screw members are each fastened, and the plurality of screw holes are arranged at circumferential positions different from the plurality of teeth portions when viewed in the axial direction. (4) The motor according to (3), wherein each of the screw holes is a hole that penetrates the base in the axial direction. (5) The motor according to (3) or (4), wherein the base has a plurality of recesses that are recessed from one axial side surface to the other axial side, and the plurality of recesses overlap with the plurality of teeth portions when viewed in the axial direction. (6) The motor according to any one of (3) to (5), wherein the base is an annular shape surrounding the central axis, and the plurality of screw holes are positioned radially inward from the radially outer edge of the base and radially outward from the radially inner edge of the base. (7) The motor according to (6), wherein the plurality of screw holes are located radially outward from the radial center between the radially outer edge of the base and the radially inner edge of the base.(8) The motor according to (7), wherein the plurality of screw holes are located radially inward from the radial center between the radial outer edge of the base and the radial inner edge of the base and the radial center between the radial outer edge of the base. (9) The motor according to any one of (1) to (8), wherein the stator has a plurality of second core members separate from the first core member, the plurality of second core members are annular in shape surrounding the ends of the plurality of teeth on the other axial side, the inner circumferential surface of each second core member is in contact with the outer circumferential surface of each tooth, the outer circumferential surface of each second core member is an inclined surface that approaches each tooth in a direction perpendicular to the axial direction as it extends toward the other axial side, and the resin part is in contact with at least a portion of the inclined surface of each second core member. (10) The motor according to (9), wherein the inclined surface of each second core member is annular and surrounds each tooth portion, and the resin portion is in contact with the inclined surface of each second core member over a circumference surrounding the inclined surface. (11) The motor according to (9) or (10), wherein the inner circumferential surface of each second core member has a pair of first sides located on both sides in the circumferential direction, a second side located radially outward, and a pair of third sides located axially between each of the pair of first sides and the second side, and the pair of third sides approach each other circumferentially as they extend radially outward. (12) The motor according to any one of (1) to (11), comprising two stators arranged axially on either side of the rotor, wherein the plurality of screw members for fixing one stator to the housing and the plurality of screw members for fixing the other stator to the housing overlap axially.

[0054] The configurations and methods described herein can be combined as appropriate, within the bounds of non-inconsistency.

[0055] 10...Housing, 11a, 11f...Core support, 11c, 11h...Outer wall, 11d, 11i...Inner wall, 21...Rotor, 30, 30a, 30b...Stator, 31...First core member, 31a...Base, 31b...Recess, 32...Second core member, 32a...Inclined surface, 32b, 32c...First side, 32d...Second side, 32e, 32f...Third side, 34...Coil, 35...Teeth part, 36...Screw hole, 50a, 50b...Resin part, 60a, 60b...Screw member, 100...Motor, C1, C2...Center, J...Central axis

Claims

1. A motor comprising: a rotor rotatable about a central axis; an annular stator located on one axial side of the rotor and surrounding the central axis; a housing to which the stator is fixed; and a resin part in which at least a portion of the stator is embedded, wherein the stator comprises: a first core member having a plurality of teeth extending in the axial direction and spaced apart in the circumferential direction; and a plurality of coils attached to each of the plurality of teeth, wherein the resin part connects the housing and the stator; the housing has a core support portion located on one axial side of the stator; and the first core member is fixed to the core support portion by a plurality of screw members spaced apart about the central axis.

2. The motor according to claim 1, wherein the housing has an annular outer wall portion located radially outside the stator and surrounding the stator, and an annular inner wall portion located radially inside the stator and surrounding the central axis, and the resin portion has a portion filled in the radial space between the outer wall portion and the inner wall portion.

3. The motor according to claim 1, wherein the first core member has a base, the plurality of teeth extend from the base to the other axial direction, the base has a plurality of screw holes into which the plurality of screw members are each tightened, and the plurality of screw holes are arranged at circumferential positions different from the plurality of teeth when viewed in the axial direction.

4. The motor according to claim 3, wherein each of the screw holes is a hole that penetrates the base in the axial direction.

5. The motor according to claim 3, wherein the base portion has a plurality of recesses that are recessed from one axial side surface to the other axial side, and the plurality of recesses overlap with the plurality of teeth portions when viewed in the axial direction.

6. The motor according to claim 3, wherein the base is an annular shape surrounding the central axis, and the plurality of screw holes are arranged at positions radially inward from the radially outer edge of the base and radially outward from the radially inner edge of the base.

7. The motor according to claim 6, wherein the plurality of screw holes are located radially outward from the radial center between the radial outer edge of the base and the radial inner edge of the base.

8. The motor according to claim 7, wherein the plurality of screw holes are located radially inward from the radial center between the radial outer edge of the base and the radial inner edge of the base and the radial center between the radial outer edge of the base.

9. The motor according to any one of claims 1 to 8, wherein the stator has a plurality of second core members separate from the first core member, the plurality of second core members are annular in shape, each encircling the other axial end of the plurality of teeth portions, the inner circumferential surface of each second core member is in contact with the outer circumferential surface of each teeth portion, the outer circumferential surface of each second core member has an inclined surface that approaches each teeth portion in a direction perpendicular to the axial direction as it extends toward the other axial side, and the resin portion is in contact with at least a portion of the inclined surface of each second core member.

10. The motor according to claim 9, wherein the inclined surface of each second core member is annular in shape surrounding each tooth portion, and the resin portion is in contact with the inclined surface of each second core member over a circumference surrounding the inclined surface.

11. The motor according to claim 9, wherein the inner circumferential surface of each second core member has a pair of first side surfaces located on both sides in the circumferential direction, a second side surface located radially outward, and a pair of third side surfaces located axially between each of the pair of first side surfaces and the second side surface, and the pair of third side surfaces move closer to each other in the circumferential direction as they extend radially outward.

12. The motor according to any one of claims 1 to 8, comprising two stators arranged axially on either side of the rotor, wherein the plurality of screw members for fixing one stator to the housing and the plurality of screw members for fixing the other stator to the housing overlap in the axial direction.

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