Electric motor

Abstract

Electric motor (1) which has the following features: a stationary section (2); and a rotating section (3) which is rotatably supported by the stationary section (2), centered on a central axis (9) which extends upwards and downwards, wherein the stationary section (2) comprises the following features: a cylindrical bearing housing (22) which extends in an axial direction around the central axis (9), and a stator (24) which is arranged in a radial direction on an outside of the bearing housing (22), wherein the stator (24) comprises the following features: a stator core (41), which is a magnetic body, an insulator (42) which is an insulating body that covers at least part of the stator core (41) and a conductor which is wound around the stator core (41) via the insulator (42), wherein the bearing housing (22) comprises the following features: a first inner circumferential surface (50) that holds a bearing (23), and a first outer circumferential surface (51) which is in direct contact with the insulator (42) or via an adhesive (71) and wherein a surface roughness of the first outer circumferential surface (51) is greater than a surface roughness of the first inner circumferential surface (50), wherein an elastic adhesive (71) is arranged between the bearing housing (22) and the stator (24), wherein the stator core (41) comprises a plurality of second excluded sections (413) which are excluded on an inner circumferential surface in the radial direction to an outer surface, and wherein the elastic adhesive (71) is positioned in the second excluded sections (413).

Description

[0001] The present disclosure relates to an electric motor.

[0002] In related technology, an electric motor is known with a structure in which a bearing is held by a cylindrical bearing housing and a stator is fixed to an outer circumferential surface of the bearing housing. An electric motor of related technology is described, for example, in the Japanese unexamined patent application publication No. JP 2013-165 620 A.

[0003] The electric motor generates torque through magnetic attraction and repulsion between the stator and rotor. When the electric motor is driven, the stator can vibrate due to this magnetic attraction and repulsion. This vibration can also be a source of noise. One method to suppress stator vibration is to place an elastic adhesive material, capable of absorbing the vibration, between the bearing housing and the stator. However, this elastic adhesive requires a long curing time. Therefore, it is necessary to prevent the stator from shifting relative to the bearing housing during the curing process.

[0004] Furthermore, regardless of whether the elastic adhesive is placed in between or not, there is a need to suppress the positional deviation of the stator in relation to the bearing housing.

[0005] JP 2013-165620A discloses a brushless motor and a blower. US 2016 / 0190875A1 discloses a spindle motor and a plate drive device. JP H08-103045A discloses a spindle motor. CN 205231904U discloses a motor. US 4209721A discloses an external rotor motor. CN 212323888U discloses a motor with a plastic housing and high mounting thickness. JP H05-15115A discloses a blower motor.

[0006] The object of the present invention is to create an electric motor with improved characteristics.

[0007] The problem is solved by an electric motor according to claim 1 and according to claim 2.

[0008] An exemplary embodiment of the disclosure is an electric motor comprising a stationary section and a rotating section rotatably supported by the stationary section centered on a central axis extending upwards and downwards. The stationary section comprises a cylindrical bearing housing extending axially around the central axis and a stator arranged radially on an outer surface of the bearing housing. The stator comprises a stator core, which is a magnetic body, an insulator, which is an insulating body covering at least a portion of the stator core, and a conductor wound around the stator core over the insulator. The bearing housing comprises a first inner circumferential surface that holds a bearing and a first outer circumferential surface that is in direct contact with the insulator or in contact with it via an adhesive.The surface roughness of the first outer circumferential surface is greater than the surface roughness of the first inner circumferential surface. An elastic adhesive is arranged between the bearing housing and the stator, wherein the stator core comprises a plurality of second recessed sections that are recessed on an inner circumferential surface in the radial direction to an outer surface, and wherein the elastic adhesive is positioned in the second recessed sections.

[0009] The above and other elements, features, steps, characteristics and advantages of the present disclosure will become apparent from the following detailed description of preferred embodiments with reference to the attached drawings.

[0010] Preferred embodiments of the present invention are explained in more detail below with reference to the accompanying drawings. These show: Fig. 1. A longitudinal section view of an electric motor; Fig. 2 a longitudinal section view of a bearing housing; Fig. 3 a side view of the bearing housing; Fig. 4 a top view of the bearing housing and a stator; Fig. 5 a partial sectional view of the bearing housing and the stator; Fig. 6 a perspective partial view of the bearing housing and stator interrupted along a plane containing a central axis; Fig. 7 a side view of a bearing housing according to a modification example; Fig. 8 A side view of a bearing housing of a modification example.

[0011] Exemplary embodiments of the disclosure are described below with reference to the drawings. Furthermore, in the present application, a direction parallel to a central axis of an electric motor is referred to as an "axial direction," a direction orthogonal to the central axis of the electric motor is referred to as a "radial direction," and a direction along a circular arc centered on the central axis of the electric motor is referred to as a "circumferential direction." In addition, the present application describes a shape and a positional relationship of each section, wherein the axial direction is an upward and downward direction, and a gripper section side is at the top with respect to a stator core.However, it merely serves the expediency of the explanation to define the direction upwards and downwards, which does not restrict the direction during the manufacture and use of the electric motor according to the invention.

[0012] Furthermore, in Revelation, a "parallel direction" also includes an essentially parallel direction. Similarly, in Revelation, an "orthogonal direction" also includes an essentially orthogonal direction.

[0013] Fig. Figure 1 is a longitudinal sectional view of an electric motor 1 according to an exemplary embodiment of the disclosure. As shown in Fig. As shown in Figure 1, the electric motor 1 comprises a stationary section 2 and a rotating section 3. The stationary section 2 is fixed to a frame of a device (hereinafter referred to as an "actual machine") to which the electric motor 1 is attached. The rotating section 3 is rotatably supported by the stationary section 2.

[0014] The stationary section 2 of the embodiment comprises a base plate 21, a bearing housing 22, a pair of bearings 23, a stator 24 and a circuit board 25.

[0015] The base plate 21 is a plate-like component that extends perpendicular to a central axis 9. The base plate 21 is fixed to the frame of the actual machine, for example, by screws. The base plate 21 has a circular hole 210 in its center. It also has a cylindrical retaining section 211 that is raised upwards around the circular hole 210. The base plate 21 can be made of a metal, such as iron. However, the material is not limited to metal, and resin can also be used.

[0016] The bearing housing 22 is a component that holds the pair of bearings 23. The bearing housing 22 can be made of a metal such as stainless steel or brass. However, the material is not limited to metal, and resin can also be used. The bearing housing 22 extends axially in a cylindrical shape around the central axis 9. A lower end section of the bearing housing 22 is inserted into the circular hole 210 of the base plate 21 and is fixed to the retaining section 211.

[0017] The pair of bearings 23 is positioned radially on an inner surface of the bearing housing 22. The pair of bearings 23 is also spaced apart vertically. Each bearing 23 is, for example, a ball bearing. An outer ring of each bearing 23 is fixed to an inner circumferential surface of the bearing housing 22. An inner ring of each bearing 23 is fixed to an outer circumferential surface of a shaft 31, which is described below. In this embodiment, the outer ring of an upper bearing 23 is pressed axially by a preload spring 231. Therefore, the bearing 23 is positioned axially.

[0018] The stator 24 is an armature that generates a magnetic flux according to a drive current. The stator 24 is arranged radially on an outer surface of the bearing housing 22. As shown in Fig. As shown in Figure 1, the stator 24 comprises a stator core 41, an insulator 42 and a coil 43.

[0019] The stator core 41 is a magnetic body. For example, a laminated steel plate is used as the stator core 41. The stator core 41 comprises an annular core back 411 and a plurality of teeth 412. The core back 411 is fixed to the outer circumferential surface of the bearing housing 22. The plurality of teeth 412 project radially from the core back to the outer surface. The insulator 42 is an insulating body. Resin, for example, is used as a material for the insulator 42. The insulator 42 covers at least part of the stator core 41. The coil 43 is formed from a conductor that is wound around the teeth 412 over the insulator 42.

[0020] The circuit board 25 is arranged essentially perpendicular to the central axis 9 on a top side of the base plate 21 and a bottom side of the stator 24. The circuit board 25 is fixed, for example, to the insulator 42. An electrical circuit for supplying a drive current to the coil 43 is attached to the circuit board 25. An end section of the conductor forming the coil 43 is electrically connected to a terminal provided in the circuit board 25.

[0021] The rotating section 3 of the embodiment comprises the shaft 31, a fixing ring 32, a hub 33 and a rotor magnet 34.

[0022] The shaft 31 is a column-shaped component arranged along the central axis 9. The shaft 31 is made of a metal, such as stainless steel. It is rotatably supported by a pair of bearings 23 centered on the central axis 9. An upper end section of the shaft 31 is positioned above the upper bearing 23. The retaining ring 32 is an annular metal component fixed to the upper end section of the shaft 31.

[0023] The hub 33 is an annular component that holds the rotor magnet 34. The hub 33 is made of a metal, such as iron. It comprises a disk section 331 and a cylindrical section 232. The disk section 331 extends essentially perpendicular to the central axis 9 above the stator 24. An inner circumferential section of the disk section 331 is fixed to the retaining ring 32. That is, the hub 33 is fixed to the shaft 31 via the retaining ring 32. The cylindrical section 331 extends downwards from an outer circumferential section of the disk section 331.

[0024] The rotor magnet 34 is fixed to an inner circumferential surface of the cylindrical section 332. The rotor magnet 34 can be a ring-shaped magnet or a plurality of magnets arranged circumferentially. An end surface of the teeth 412 on the outside, radially oriented, and a surface of the rotor magnet 34 on the inside, radially oriented, face each other radially with a small gap between them. Furthermore, an N-pole and an S-pole are alternately magnetized circumferentially on a surface of the rotor magnet 34 on the inside, radially oriented.

[0025] When the drive current is supplied from the circuit board 25 to the coil 43 of the stator 24, a magnetic flux is generated in each tooth 412 of such an electric motor 1. A torque in the circumferential direction is generated by a rotating magnetic field that is created between the teeth 412 and the rotor magnet 34. As a result, the rotating section 3 rotates with respect to the stationary section 2 centered on the central axis 9.

[0026] The following describes in more detail a fixing structure between the bearing housing 22 and the stator 24. Fig. Figure 2 is a longitudinal section view of the bearing housing 22. Fig. Figure 3 is a side view of the bearing housing 22. Fig. Figure 4 is a top view of the bearing housing 22 and the stator 24. Fig. Figure 5 is a partial sectional view of the bearing housing 22 and the stator 24. Fig. Figure 6 is a perspective partial view of the bearing housing 22 and the stator 24 interrupted along a plane containing the central axis 9.

[0027] As it is in Fig. 2 and Fig. As shown in Figure 3, the bearing housing 22 comprises a first inner circumferential surface 50, a first outer circumferential surface 51, and a second outer circumferential surface 52. The first inner circumferential surface 50 is a surface for holding the bearing 23 on the inner circumferential surface of the bearing housing 22. More precisely, the outer ring of the bearing 23 is fixed to the first inner circumferential surface 50. To position the bearing 23 with extreme accuracy relative to the bearing housing 22, it is preferred that the first inner circumferential surface 50 be machined to a precise circle with high accuracy and have a low surface roughness.

[0028] The first outer circumferential surface 51 is a surface that is in contact with the insulator 42 on the outer circumferential surface of the bearing housing 22. The second outer circumferential surface 52 is a surface on which the stator core 41 is fixed to the outer circumferential surface of the bearing housing 22. The second outer circumferential surface 52 is positioned lower than the first outer circumferential surface 51 in the axial direction.

[0029] As it is in Fig. As shown in Figures 4 to 6, the insulator 42 of the exemplary embodiment comprises a plurality of claw or gripper sections 421. The plurality of gripper sections 421 are arranged at uniform intervals in the circumferential direction. Furthermore, each gripper section 421 projects radially from an annular inner circumferential surface of the insulator 42 to the inner surface. An end surface 80 of each gripper section 421 on the inner surface in the radial direction is in contact with the first outer circumferential surface 51 of the bearing housing 22. The first outer circumferential surface 51 and the end surface 80 of the gripper section 421 can, however, be in direct contact with each other or can be in contact with each other via an adhesive.

[0030] Furthermore, as it is in Fig. As shown in Figure 3, the first outer circumferential surface 51 of the bearing housing 22 is formed from a plurality of grooves 60. Therefore, the surface roughness of the first outer circumferential surface 51 is greater than the surface roughness of the first inner circumferential surface 50. That is, the first outer circumferential surface 51 is rougher than the first inner circumferential surface 50. The end surface 80 of the gripper section 421 on the inside in the radial direction is in contact with the first outer circumferential surface 51, which includes such grooves 60. The coefficient of friction between the first outer circumferential surface 51 and the gripper section 421 is higher due to the plurality of grooves 60 than it would be without the grooves 60. Therefore, the positional deviation of the gripper section 421 with respect to the first outer circumferential surface 51 is suppressed. That is, the positional deviation of the stator 24 with respect to the bearing housing 22 is suppressed.

[0031] For example, in a case where the insulator 42 is fixed to the bearing housing 22 by means of an interference fit, excessive stress is applied to the bearing housing 22 or the insulator 42, which can cause deformation, breakage, or the like. On the other hand, in the embodiment, the coefficient of friction between the first outer circumferential surface 51 and the gripper section 421 is high due to the plurality of grooves 60, so that it is possible to suppress the positional deviation of the stator 24 with respect to the bearing housing 22 by a low contact force.

[0032] In this embodiment, the majority of grooves 60 form a crosshatch pattern. That is, the majority of grooves 60 comprise a majority of first grooves 61 inclined to the axial direction and a majority of second grooves 62 extending at an angle different from that of the first grooves 61. The majority of first grooves 61 and the majority of second grooves 62 intersect each other. The grooves 60 are formed, for example, by knurling. Not only the circumferential positional deviation of the stator 24 with respect to the bearing housing 22, but also the axial positional deviation is suppressed by forming the majority of grooves 60 in the crosshatch pattern.

[0033] As it is in Fig. As shown in Figure 5, an elastic silicone-based adhesive 71 is arranged between the second outer circumferential surface 52 of the bearing housing 22 and the inner circumferential surface of the stator core 41. The elastic adhesive 71 serves to fix the stator core 41 to the bearing housing 22 and to absorb the vibration generated in the stator core 41. The transmission of vibration from the stator core 41 to the bearing housing 22 is suppressed by the use of the elastic adhesive 71. As a result, vibration and noise are reduced during operation of the electric motor 1.

[0034] However, the elastic adhesive 71 can have a long curing time after coating. Therefore, after applying the elastic adhesive 71, it is necessary to suppress the positional deviation of the stator 24 relative to the bearing housing 22 until the elastic adhesive 71 has cured. In the exemplary embodiment, the majority of gripper sections 421 of the insulator 42 are in contact with the first outer circumferential surface 51 of the bearing housing 22, as described above. The coefficient of friction between the bearing housing 22 and the stator 24 is increased by the majority of grooves 60. Therefore, it is possible to suppress the positional deviation of the stator 24 relative to the bearing housing 22 during the curing of the elastic adhesive 71.

[0035] In this embodiment, the majority of grooves 60 are provided only on the first outer circumferential surface 51 and the second outer circumferential surface 52. Therefore, the surface roughness of the first outer circumferential surface 51 is greater than the surface roughness of the second outer circumferential surface 52. Consequently, of the first outer circumferential surface 51 and the second outer circumferential surface 52, only the first outer circumferential surface 51 is formed, thus reducing the manufacturing costs of the bearing housing 22.

[0036] As it is in Fig. As shown in Figures 4 to 6, the gripper section 421 of the exemplary embodiment comprises a gripper section body 81 and a gripper wall section 82. The gripper section body 81 extends radially from the annular inner circumferential surface of the insulator 42 to the inner surface. The gripper wall section 82 extends radially upwards from an end section of the gripper section body 81 on the inner surface. The surface of the gripper wall section 82 on the inner surface becomes the end surface 80 of the gripper section 421 on the inner surface. As described above, it is possible to widen a region of the end surface 80 by extending the gripper wall section 82. Therefore, it is possible to increase the contact area between the first outer circumferential surface 51 and the end surface 80.As a result, the positional deviation of the stator 24 in relation to the bearing housing 22 can be further suppressed.

[0037] Furthermore, the gripper wall section 82 can be slightly bent. Therefore, the gripper wall section 82 can be in elastic contact with the first outer circumferential surface 51. This means that it is possible to press the end surface 80 of the gripper section 421 against the first outer circumferential surface 51. Therefore, the contact area between the first outer circumferential surface 51 and the end surface 80 is further increased. In addition, the positional deviation of the stator 24 with respect to the bearing housing 22 can be further suppressed.

[0038] Furthermore, as it is in Fig. As shown in Figure 4, the end surface 80 of the gripper section 421 of the exemplary embodiment is an excluding curved surface in the top view. The radius of curvature of the end surface 80, which is a curved surface, is the same as that of the first outer circumferential surface 51. The term "same," as used herein, includes both a case of "completely identical" and a case of "essentially identical." As described above, if the radius of curvature of the end surface 80 and the radius of curvature of the first outer surface 51 are the same, the contact area between the end surface 80 and the first outer circumferential surface 51 is increased. Therefore, a frictional force generated between the end surface 80 and the first outer circumferential surface 51 is further increased. As a result, the positional deviation of the stator 24 with respect to the bearing housing 22 is further suppressed.

[0039] Furthermore, the radius of curvature of the end surface 80 of the gripper section 421 can be smaller than that of the first outer circumferential surface 51. In this case, an end section of the end surface 80 is gripped circumferentially by the first outer circumferential surface 51. Therefore, the positional deviation of the stator 24 relative to the bearing housing 22 is further suppressed circumferentially. In particular, if the end section of the end surface 80 fits circumferentially into the grooves 60 of the first outer circumferential surface 51, the positional deviation of the stator 24 relative to the bearing housing 22 is further suppressed circumferentially.

[0040] As it is in Fig. 2, Fig. 3, Fig. 5 and Fig. As shown in Figure 6, the bearing housing 22 of the exemplary embodiment also includes an annular first recessed section 221 on its outer circumferential surface. The first recessed section 221 is recessed from the outer circumferential surface of the bearing housing 22 in the radial direction to the inner surface. The first outer circumferential surface 51 is positioned within the first recessed section 221. Therefore, the end surface 80 of the gripper section 421 is received within the first recessed section 221 and is in contact with the first outer circumferential surface 51. As described above, if the end surface 80 of the gripper section 421 is received within the first recessed section 221, the axial positional deviation of the gripper section 421 relative to the bearing housing 22 can be suppressed. Therefore, the axial positional deviation of the stator 24 relative to the bearing housing 22 can be suppressed.

[0041] Furthermore, in this embodiment, a lower section of the end surface 80 of the gripper section 421 has a smooth curved surface 83. When the stator 24 is inserted into the bearing housing 22, the curved surface 83 can slide and move on an outer surface of the bearing housing 22. Therefore, it is possible to suppress gripping of the gripper section 421 by the bearing housing 22 and to prevent breakage of the gripper section 421. Moreover, the end surface 80 of the gripper section 421 can be readily accommodated by providing the curved surface 83 in the first recessed section 221. As shown in Fig. As shown in Figure 5, it is also preferable that an upper section of the end surface 80 of the gripper section 421 has a rectangular shape. It is possible to prevent the gripper section 421 from disengaging axially upwards from the first excluded section 221 by making the upper section angled.

[0042] As it is in Fig. As shown in Figure 4, the stator core 41 of the exemplary embodiment also has a plurality of second recessed sections 413 on its inner circumferential surface. The plurality of second recessed sections 413 are arranged at uniform intervals in the circumferential direction. Every second recessed section 413 is recessed from the inner circumferential surface of the stator core 41 in the radial direction to the outside. The elastic adhesive 71 is positioned in the second recessed section 413. As described above, if the second recessed section 413, which holds the elastic adhesive 71, is provided on the inner circumferential surface of the stator core 41, fluctuations in the amount of elastic adhesive 71 arranged between the bearing housing 22 and the stator core 41 can be suppressed.Furthermore, a section other than the second excluded section 413 in the inner circumferential surface of the stator core 41 is in direct contact with the second outer circumferential surface 52 of the bearing housing 22. Therefore, the stator core 41 can be positioned with higher accuracy relative to the bearing housing 22.

[0043] As it is in Fig. As shown in Figure 4, in this embodiment the number of second recessed sections 413 contained in the stator core 41 and the number of gripper sections 421 contained in the insulator 42 are equal. The gripper section 421 and the second recessed section 413 are arranged in overlapping positions in a top view. Therefore, in a manufacturing step of the electric motor 1, it is easy to hold the inner circumferential section of the stator 24 while bypassing the gripper section 421 and the second recessed section 413. For example, when forming the coil 43 of the stator 24, a clamping device of a winding machine can hold the inner circumferential section of the stator 24 while bypassing the gripper section 421 and the second recessed section 413.

[0044] As it is in Fig. 2, Fig. 3, Fig. 5 and Fig. As shown in Figure 6, the bearing housing 22 of the exemplary embodiment also has an annular stepped surface 222 on its outer circumferential surface. The stepped surface 222 extends radially from the lower end section of the second outer circumferential surface 52 to the outer side. A portion of the stepped surface 222 faces a portion of the lower surface of the stator core 41 in the axial direction. The stepped surface 222 suppresses the axial positional deviation of the stator 24 relative to the lower side of the bearing housing 22.

[0045] As it is in Fig. As shown in Figure 5, a portion of the elastic adhesive 71 can be positioned between the lower surface of the stator core 41 and the stepped surface 222. Therefore, the transmission of vibration from the lower surface of the stator core 41 to the bearing housing 22 is also suppressed. Consequently, vibration and noise during operation of the electric motor 1 can be further reduced.

[0046] Although an exemplary embodiment of the present disclosure is described above, the present disclosure is not limited to the embodiments described above.

[0047] Fig. 7 is a side view of a bearing housing 22A according to an exemplary modification example of the disclosure. In the example of Fig. 7 A first outer circumferential surface 51A of the bearing housing 22A is formed with a plurality of grooves 60A exhibiting a vertical stripe pattern. That is, the plurality of grooves 60A extend in the axial direction and are arranged in the circumferential direction. As described above, if the plurality of grooves 60A are formed in the vertical stripe pattern, one direction of each groove is perpendicular to the circumferential direction. Therefore, the effect of suppressing the positional deviation of the stator with respect to the bearing housing 22A in the circumferential direction is further improved.

[0048] Fig. Figure 8 is a side view of a bearing housing 22B according to another exemplary modification example of the disclosure. In the example of Fig.8 is a first outer circumferential surface 51B of the bearing housing 22B formed with a plurality of grooves 60B which have a spiral pattern. That is, the plurality of grooves 60B extend centered on the central axis in a spiral shape. Even with such a pattern, the positional deviation of the stator with respect to the bearing housing 22B can be suppressed.

[0049] Furthermore, to increase the surface roughness of the first outer circumferential surface in the exemplary embodiment and the modification examples, a majority of grooves are formed on the first outer circumferential surface. However, the surface roughness of the first outer circumferential surface can be increased by another method. For example, a majority of protrusions can be formed on the first outer circumferential surface. Additionally, a discontinuous surface roughness can be created by using a grinding wheel or the like.

[0050] Furthermore, in the embodiment described above, the elastic adhesive is arranged between the bearing housing and the stator core. However, the adhesive arranged between the bearing housing and the stator core can be a different type of adhesive. Additionally, the bearing housing and the stator core can be in direct contact with each other without using the adhesive. However, in a case where an adhesive that requires time to cure, such as an elastic adhesive or a thermosetting adhesive, is used, it is necessary to suppress the positional deviation of the stator core relative to the bearing housing until curing is complete. Therefore, the present disclosure is particularly useful.

[0051] Furthermore, in the embodiment described above, the gripper section projecting from the annular inner circumferential surface of the insulator is in contact with the first outer circumferential surface. However, the contact section of the insulator with the first outer circumferential surface can also be an annular inner circumferential surface of the insulator. Additionally, in the embodiment described above, the upper section of the insulator is in contact with the first outer circumferential surface. However, the lower section of the insulator can also be in contact with the first outer circumferential surface by providing the first outer circumferential surface beneath the stator core.

[0052] The application of an exemplary electric motor of the present disclosure is not particularly limited. An exemplary electric motor of the present disclosure may, for example, be a fan motor with an impeller attached to the rotating section.

[0053] Furthermore, the detailed shape of each component may differ from the shape shown in each drawing of this disclosure. In addition, each element appearing in the embodiment and the modification examples described above may be combined accordingly within a range where no contradiction arises.

[0054] The present disclosure can, for example, be applied to an electric motor.

[0055] Features of the preferred embodiments described above and their modifications can be combined accordingly, as long as no conflict arises.

[0056] Although preferred embodiments of the present disclosure have been described above, it is clear that variations and modifications are obvious to those skilled in the art without altering the scope and nature of the present disclosure. The scope of the present disclosure is therefore defined solely by the following claims.

Claims

[1] Electric motor (1) having the following features: a stationary section (2); and a rotating section (3) rotatably supported by the stationary section (2), centered on a central axis (9) extending upwards and downwards, wherein the stationary section (2) comprises the following features: a cylindrical bearing housing (22) extending in an axial direction around the central axis (9), and a stator (24) arranged in a radial direction on an outer side of the bearing housing (22), wherein the stator (24) comprises the following features: a stator core (41) which is a magnetic body, an insulator (42) which is an insulating body covering at least a part of the stator core (41) and a conductor wound around the stator core (41) via the insulator (42), wherein the bearing housing (22) comprises the following features: a first inner peripheral surface (50) supporting a bearing (23), and a first outer peripheral surface (51) which is in contact with the insulator (42) directly or via an adhesive (71) and wherein a surface roughness of the first outer peripheral surface (51) is greater than a surface roughness of the first inner peripheral surface (50), wherein an elastic adhesive (71) is arranged between the bearing housing (22) and the stator (24), wherein the stator core (41) comprises a plurality of second recessed portions (413) recessed on an inner peripheral surface in the radial direction to an outside, and wherein the elastic adhesive (71) is positioned in the second recessed portions (413). [2] Electric motor (1) having the following features: a stationary section (2); and a rotating section (3) rotatably supported by the stationary section (2), centered on a central axis (9) extending upwards and downwards, wherein the stationary section (2) comprises the following features: a cylindrical bearing housing (22) extending in an axial direction around the central axis (9), and a stator (24) arranged in a radial direction on an outer side of the bearing housing (22), wherein the stator (24) comprises the following features: a stator core (41) which is a magnetic body, an insulator (42) which is an insulating body covering at least a part of the stator core (41) and a conductor wound around the stator core (41) via the insulator (42), wherein the bearing housing (22) comprises the following features: a first inner peripheral surface (50) supporting a bearing (23), and a first outer peripheral surface (51) which is in contact with the insulator (42) directly or via an adhesive (71) and wherein a surface roughness of the first outer peripheral surface (51) is greater than a surface roughness of the first inner peripheral surface (50), wherein the insulator (42) comprises the following features: a gripper portion (421) projecting in the radial direction to an inner side, and wherein the gripper portion (421) comprises an end surface (80) which is in contact with the first outer peripheral surface (51) directly or via an adhesive (71), wherein the stator core (41) has a plurality of second recessed portions (413) recessed on an inner peripheral surface in the radial direction to an outside, and wherein the gripper portion (421) and a corresponding one of the second recessed portions (413) overlap each other in plan view. [3] Electric motor (1) according to claim 1, wherein the bearing housing (22) further comprises the following features: a second outer peripheral surface (52) which is in contact directly or via an adhesive (71) with an inner peripheral surface of the stator core (41) and wherein the surface roughness of the first outer peripheral surface (51) is greater than a surface roughness of the second outer peripheral surface (52). [4] Electric motor (1) according to one of claims 1 or 3, wherein the first outer peripheral surface (51) has a plurality of grooves (60). [5] Motor (1) according to claim 4, wherein the plurality of grooves (60) comprises the following features: a plurality of first grooves (61) extending obliquely with respect to the axial direction, and a plurality of second grooves (62) extending at an angle different from an angle of the first grooves (61), and wherein the plurality of first grooves (61) and the plurality of second grooves (62) intersect each other. [6] Electric motor (1) according to claim 4, wherein the plurality of grooves (60) extend in the axial direction and are arranged in a circumferential direction. [7] Electric motor (1) according to claim 4, wherein the plurality of grooves (60) extend spirally centered on the central axis (9). [8] Electric motor (1) according to one of claims 1 or 3 to 7, wherein the insulator (42) comprises the following features. a gripper portion (421) projecting in the radial direction to an inner side, and wherein the gripper portion (421) comprises an end surface (80) in contact with the first outer peripheral surface (51) directly or via an adhesive (71). [9] Electric motor (1) according to claim 2 or 8, wherein the insulator (42) comprises a plurality of gripper sections (421). [10] Electric motor (1) according to claim 9, wherein the plurality of gripper portions (421) are arranged at equal intervals in a circumferential direction. [11] Electric motor (1) according to one of claims 2 or 8 to 10, wherein the end surface (80) of the gripper portion (421) is a recessed curved surface in plan view and wherein a radius of curvature of the curved surface is the same as a radius of curvature of the first outer peripheral surface (51). [12] Electric motor (1) according to one of claims 2 or 8 to 10, wherein the end surface (80) of the gripper portion (421) in plan view is a recessed curved surface (83) and wherein a radius of curvature of the curved surface (83) is smaller than a radius of curvature of the first outer peripheral surface (51). [13] Electric motor (1) according to one of claims 2 or 8 to 12, wherein the gripper section (421) comprises the following features: a gripper section body (81) extending in the radial direction to the inside, and a gripper wall portion (82) extending from an end portion of the gripper portion body (81) on the inside in the radial direction to an upper surface of the gripper portion body (81) in the axial direction, and wherein the end surface (80) is a surface of the gripper wall portion (82) on the inside in the radial direction. [14] Electric motor (1) according to claim 13, wherein the stator core (41) comprises a plurality of second recessed portions (413) recessed on an inner peripheral surface (50) in the radial direction to an outside, and wherein the elastic adhesive (71) is positioned in the second recessed portions (413). [15] Electric motor (1) according to one of claims 8 to 14, wherein the stator core (41) has a plurality of second recessed portions (413) recessed on an inner peripheral surface (50) in the radial direction to an outside, and wherein the gripper portion (421) and a corresponding one of the second recessed portions (413) overlap each other in plan view. [16] Electric motor (1) according to claim 1, wherein the bearing housing (22) comprises a stepped surface (222) facing a lower surface of the stator core (41) in the axial direction and wherein a part of the elastic adhesive (71) is arranged between the lower surface of the stator core (41) and the stepped surface (222).

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