Air blowing device and hair dryer

Abstract

To provide an air blowing device that can restrain vibration and noise.SOLUTION: An air blowing device comprises an impeller, a motor for rotating the impeller, and a housing for housing the impeller and the motor. The motor has a rotor, and a stator. The rotor has a shaft, and a rotor magnet fixed to a radial outside surface of the shaft. The impeller is fixed at a position above a fixing position of the rotor magnet out of the radial outside surface of the shaft. The housing has a first bearing 301 for rotatably supporting the shaft at a position above the fixing position of the rotor magnet and below a fixing position of the impeller, and a second bearing for rotatably supporting the shaft at a position below the fixing position of the rotor magnet. A gravity center position P of the impeller is located at a position overlapping with an upper end of the first bearing, or a position below the upper end of the first bearing when viewed from a radial direction.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a blower device and a hair dryer. [Background technology]

[0002] A conventional blower device includes an impeller that is fixed to a shaft and rotates together with the shaft (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-669 A Summary of the Invention [Problem to be solved by the invention]

[0004] For example, the impeller is fixed to the end of the shaft. In this configuration, the end of the shaft vibrates when the impeller rotates. If the end of the shaft vibrates to a large extent, the vibration and noise of the blower increases.

[0005] The present invention aims to suppress vibration and noise from a blower device. [Means for solving the problem]

[0006] An exemplary blower device of the present invention includes an impeller rotatable around a central axis extending vertically, a motor for rotating the impeller, and a housing for accommodating the impeller and the motor. The motor includes a rotor rotatable around the central axis, and a stator for rotating the rotor. The rotor includes a shaft extending along the central axis, and a rotor magnet fixed to a radially outer surface of the shaft. The impeller is fixed to a position on the radially outer surface of the shaft above a fixed position of the rotor magnet. The housing includes a first bearing for rotatably supporting the shaft at a position above the fixed position of the rotor magnet and below the fixed position of the impeller, and a second bearing for rotatably supporting the shaft at a position below the fixed position of the rotor magnet. The center of gravity of the impeller is located at a position overlapping an upper end of the first bearing or below an upper end of the first bearing when viewed from the radial direction.

[0007] An exemplary hair dryer of the present invention includes the above-described blowing device. Effect of the Invention

[0008] According to the exemplary air blower and hair dryer of the present invention, vibration and noise of the air blower can be suppressed. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is an exploded perspective view of a blower according to an embodiment. [Diagram 2] FIG. 2 is a cross-sectional view of the blower according to the embodiment. [Diagram 3] FIG. 3 is a cross-sectional perspective view of a housing according to the embodiment. [Figure 4] FIG. 4 is an enlarged cross-sectional view of a lower bush and its periphery according to the embodiment. [Diagram 5] FIG. 5 is an exploded cross-sectional view of the housing according to the embodiment. [Figure 6] FIG. 6 is a cross-sectional view that illustrates a hair dryer according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, exemplary embodiments of the present invention will be described with reference to FIGS.

[0011] In this specification, the direction in which the central axis CA of the blower 100 extends is referred to as the "axial direction," and the circumferential direction about the central axis CA is referred to as the "circumferential direction." Additionally, the direction perpendicular to the central axis CA is referred to as the "radial direction." Within the radial direction, the direction approaching the central axis CA is referred to as the "radial inward direction," and the direction moving away from the central axis CA is referred to as the "radial outward direction."

[0012] For the sake of convenience, the present specification defines the axial direction as the up-down direction, and describes the side on which the impeller 1 is disposed as the upper side of the blower device 100. However, this definition of the up-down direction does not limit the actual orientation and positional relationship of each component of the blower device 100.

[0013] <1. Configuration of the blower> Fig. 1 is an exploded perspective view of blower device 100 according to the embodiment. Fig. 2 is a cross-sectional view of blower device 100 according to the embodiment. Fig. 3 is a cross-sectional perspective view of housing 3 according to the embodiment. Fig. 4 is an enlarged cross-sectional view of lower bush 213 and its periphery according to the embodiment. Fig. 5 is an exploded cross-sectional view of housing 3 according to the embodiment. Figs. 2 to 5 correspond to a cross section of blower device 100 cut along a plane including central axis CA.

[0014] The blower device 100 includes an impeller 1, a motor 2, and a housing 3. The impeller 1 is rotatable about a central axis CA that extends vertically. The motor 2 rotates the impeller 1. The housing 3 accommodates the impeller 1 and the motor 2.

[0015] <1-1.Impeller> The impeller 1 has a base portion 11. The base portion 11 is disk-shaped with a central axis CA as its center. The base portion 11 is fixed to the motor 2. Specifically, the base portion 11 has a boss 110 at its radial center. The boss 110 is a cylindrical portion extending in the axial direction. That is, the base portion 11 has a through hole penetrating in the axial direction at its radial center. The boss 110 is fixed to a radial outer surface of a shaft 211 described later. For example, the shaft 211 is press-fitted into the through hole of the boss 110. The boss 110 is fixed to the radial outer surface of the shaft 211, whereby the impeller 1 is fixed to the shaft 211.

[0016] The impeller 1 has a cylindrical portion 12 and a plurality of rotor blades 13. The cylindrical portion 12 extends downward from the radial outer edge of the base portion 11. That is, the cylindrical portion 12 is cylindrical and centered on a central axis CA. The plurality of rotor blades 13 extend radially outward from the radial outer surface of the cylindrical portion 12 and are arranged in the circumferential direction.

[0017] Here, the center of gravity of impeller 1 is located radially inward of tubular portion 12. In a cross-sectional view of blower 100 cut along a plane including central axis CA, position P marked with a black circle in Fig. 2 is the position of the center of gravity of impeller 1. Position P of center of gravity of impeller 1 is below base portion 11 and above the lower end of tubular portion 12, and overlaps with central axis CA.

[0018] <1-2.Motor> The motor 2 includes a rotor 21 and a stator 22. The rotor 21 is rotatable about a central axis CA. The stator 22 rotates the rotor 21.

[0019] The rotor 21 has a shaft 211. The shaft 211 extends along a central axis CA. The shaft 211 is supported so as to be rotatable about the central axis CA. When the shaft 211 rotates, the impeller 1 fixed to the shaft 211 rotates together with the shaft 211. The shaft 211 also has a groove portion (reference number omitted) extending in the circumferential direction on its radially outer surface.

[0020] The rotor 21 has a rotor magnet 212. The rotor magnet 212 is cylindrical. The rotor magnet 212 is disposed radially inward of a cylindrical magnet cover 2120. As a result, the entire radial outer surface of the rotor magnet 212 is covered by the magnet cover 2120. The rotor magnet 212 is fixed to the radial outer surface of the shaft 211. The impeller 1 is fixed to a position on the radial outer surface of the shaft 211 above the fixed position of the rotor magnet 212.

[0021] For example, in the process of fixing the rotor magnet 212 to the shaft 211, an adhesive is applied to the groove portion and its periphery on the radially outer surface of the shaft 211. Then, the shaft 211 is press-fitted into the rotor magnet 212. In other words, the rotor magnet 212 is fixed to the radially outer surface of the shaft 211 with the adhesive.

[0022] The rotor 21 has a lower bush 213. The lower bush 213 is fixed to a radially outer surface of the shaft 211. The lower bush 213 is disposed below the rotor magnet 212. Specifically, the lower bush 213 is disposed axially between a second bearing 302 (described later) and the rotor magnet 212. The lower bush 213 comes into contact with a lower end of the rotor magnet 212 in the axial direction. This suppresses misalignment of the rotor magnet 212 in the axial direction.

[0023] The stator 22 is disposed radially outward of the rotor 21. The stator 22 faces the rotor 21 with a radial gap therebetween. Specifically, the stator 22 faces a radially outer surface of the rotor magnet 212 with a radial gap therebetween. The stator 22 is fixed to the housing 3. The stator 22 has a stator core 221, an insulator 222, and a coil 223.

[0024] The stator core 221 is an annular magnetic body centered on a central axis CA, and is a laminated body in which a plurality of plate-shaped electromagnetic steel sheets are laminated in the axial direction. The radially inner surface of the stator core 221 faces the rotor magnet 212 with a radial gap therebetween. The radially outer surface of the stator core 221 is fixed to the housing 3.

[0025] Insulator 222 covers at least a portion of stator core 221. Insulator 222 is an insulating member made of resin or the like. Coil 223 is formed by winding a conductive wire around stator core 221 via insulator 222. Coil 223 is electrically connected to a circuit board (not shown). Various electronic components are mounted on the circuit board.

[0026] <1-3. Housing> The housing 3 has a first bearing 301 that rotatably supports the shaft 211, and a second bearing 302 that rotatably supports the shaft 211. The first bearing 301 rotatably supports the shaft 211 at a position above the fixed position of the rotor magnet 212 and below the fixed position of the impeller 1. The second bearing 302 rotatably supports the shaft 211 at a position below the fixed position of the rotor magnet 212.

[0027] The housing 3 includes a first housing 31 and a second housing 32. The first housing 31 and the second housing 32 are each fixed to the stator 22. The second housing is disposed below the first housing 31. As a result, the first housing 31 and the second housing 32 are fastened to each other in the axial direction.

[0028] The first housing 31 holds the first bearing 301. The first housing 31 has a first holding portion 31a that holds the first bearing 301. An outer ring of the first bearing 301 is fixed to the first holding portion 31a, and an inner ring of the first bearing 301 is fixed to the radial outer surface of the shaft 211.

[0029] The second housing 32 holds the second bearing 302. The second housing 32 has a second holding portion 32a that holds the second bearing 302. An outer ring of the second bearing 302 is fixed to the second holding portion 32a, and an inner ring of the second bearing 302 is fixed to the radial outer surface of the shaft 211.

[0030] The first housing 31 has an inner cylindrical portion 311. The inner cylindrical portion 311 is cylindrical and centered on a central axis CA. The first holding portion 31a is connected to the inner cylindrical portion 311. That is, the inner cylindrical portion 311 has the first holding portion 31a at its radial center.

[0031] The inner cylindrical portion 311 covers the stator 22 from the radially outer side and holds the stator 22. Specifically, the inner cylindrical portion 311 has ribs 3110 on its radially inner surface that contact the stator 22. There are multiple ribs 3110. The multiple ribs 3110 protrude radially inward from the radially inner surface of the inner cylindrical portion 311 and extend in the axial direction. The multiple ribs 3110 are arranged in the circumferential direction. The multiple ribs 3110 come into contact with the stator 22 from the radially outer side, thereby holding the stator 22 radially inward of the inner cylindrical portion 311.

[0032] The first housing 31 has an outer cylindrical portion 312. The outer cylindrical portion 312 is cylindrical and centered on a central axis CA. The outer cylindrical portion 312 is disposed radially outward of the inner cylindrical portion 311 at a distance from the inner cylindrical portion 311. The outer cylindrical portion 312 forms an airflow passage between itself and the inner cylindrical portion 311 in the radial direction.

[0033] The first housing 31 has a stator vane 313. The stator vane 313 is disposed radially between the inner tubular portion 311 and the outer tubular portion 312. The stator vane 313 connects the inner tubular portion 311 and the outer tubular portion 312. There are multiple stator vanes 313. The multiple stator vanes 313 are arranged in the circumferential direction.

[0034] As the impeller 1 rotates, an airflow from above to below is generated radially between the inner cylindrical portion 311 and the outer cylindrical portion 312. At this time, the plurality of stator vanes 313 allows the airflow to flow smoothly radially between the inner cylindrical portion 311 and the outer cylindrical portion 312.

[0035] <2. Location of the first bearing> In a configuration in which the impeller 1 is fixed to the upper end of the shaft 211, if the upper end of the shaft 211 is not supported, the vibration and noise of the shaft 211 will increase, causing vibration and noise. On the other hand, in a configuration in which the upper end of the shaft 211 is rotatably supported by the first bearing 301 (i.e., the configuration of this embodiment), the vibration and noise caused by the rotation of the impeller 1 can be suppressed. However, if the axial distance between the center of gravity position P of the impeller 1 and the first bearing 301 is large, the effect of suppressing vibration and noise will be reduced. The larger the axial distance between the center of gravity position P of the impeller 1 and the first bearing 301, the larger the vibration of the shaft 211 will be, and the more likely it is that vibration and noise will occur. For this reason, it is preferable that the axial distance between the center of gravity position P of the impeller 1 and the first bearing 301 is small.

[0036] Therefore, in this embodiment, as shown in FIG. 2, the position of the center of gravity P of the impeller 1 is a position overlapping with the upper end of the first bearing 301 or a position lower than the upper end of the first bearing 301 when viewed from the radial direction. That is, the position of the center of gravity P of the impeller 1 overlaps with the first bearing 301 when viewed from the radial direction. This makes it difficult for the shaft 211 to vibrate when the impeller 1 rotates. As a result, vibration and noise can be suppressed. Note that the position of the center of gravity P of the impeller 1 is preferably within a range from the upper end to the lower end of the first bearing 301 when viewed from the radial direction. Therefore, in this embodiment, the position of the center of gravity P of the impeller 1 is a position overlapping with the lower end of the first bearing 301 or a position higher than the lower end of the first bearing 301 when viewed from the radial direction. This reduces the axial center-of-gravity distance between the impeller 1 and the first bearing 301, which is more effective in suppressing vibration and noise.

[0037] In addition, in this embodiment, since the radial center of the impeller 1 is hollow, more than half of the first bearing 301 from the upper end downward is disposed radially inward of the tubular portion 12. That is, the axial center of the first bearing 301 is located above the lower end of the tubular portion 12. In this embodiment, the entire first bearing 301 is disposed radially inward of the tubular portion 12 as viewed from the radial direction. This makes it easy to overlap the center of gravity P of the impeller 1 with the first bearing 301 as viewed from the radial direction. In FIG. 2, in order to clarify the lower end position of the tubular portion 12, the lower end position of the tubular portion 12 is indicated by "PL".

[0038] Furthermore, in this embodiment, the boss 110 protrudes upward from the upper surface of the base portion 11. For example, if the boss 110 is made smaller in the axial direction without protruding upward from the upper surface of the base portion 11, a space for arranging the first bearing 301 can be secured radially inward of the tubular portion 12, but the fixation of the boss 110 to the shaft 211 will be weakened. However, if the boss 110 is made larger in the axial direction radially inward of the tubular portion 12 in order to prevent the fixation of the boss 110 to the shaft 211 from being weakened, a sufficient space for arranging the first bearing 301 cannot be secured radially inward of the tubular portion 12.

[0039] On the other hand, in this embodiment, by making the boss 110 protrude upward from the upper surface of the base portion 11, it is possible to prevent the boss 110 from becoming smaller in the axial direction, while ensuring a sufficient arrangement space for the first bearing 301 radially inward of the tubular portion 12. As a result, even if the first bearing 301 is arranged radially inward of the tubular portion 12, it is possible to prevent the fixation of the boss 110 to the shaft 211 from becoming weak.

[0040] In this embodiment, the lower end of the first bearing 301 is located above the upper end of the stator vane 313. Here, in this embodiment, the impeller 1 is disposed above the stator vane 313. Therefore, by disposing the first bearing 301 such that the lower end of the first bearing 301 is located above the upper end of the stator vane 313, it is possible to easily align the center of gravity P of the impeller 1 with the first bearing 301 when viewed from the radial direction. In FIG. 2, in order to clarify the upper end position of the stator vane 313, the upper end position of the stator vane 313 is indicated by "PT".

[0041] <3. Reinforcement of the shaft with the upper bush> In a configuration in which first bearing 301 is disposed radially inward of tubular portion 12, it is necessary to displace the axial position of first bearing 301 upward. That is, the axial distance between rotor magnet 212 and first bearing 301 becomes large. In this case, unless the portion of shaft 211 between rotor magnet 212 and first bearing 301 in the axial direction is reinforced, shaft 211 may bend.

[0042] Therefore, in this embodiment, the rotor 21 has an upper bush 214. The upper bush 214 is fixed to a radially outer surface of the shaft 211. The upper bush 214 is disposed axially between the rotor magnet 212 and the first bearing 301. A gap is provided between the rotor magnet 212 and the upper bush 214 in the axial direction. However, the upper bush 214 may be in contact with the upper end of the rotor magnet 212 in the axial direction.

[0043] The upper bush 214 is disposed on the shaft 211 between the rotor magnet 212 and the first bearing 301 in the axial direction, thereby improving the rigidity of the shaft 211. This makes the shaft 211 less likely to bend.

[0044] <4. Fixing the rotor magnet with the lower bush> When the shaft 211 is press-fitted into the rotor magnet 212, the adhesive applied to the radially outer surface of the shaft 211 flows downward and reaches the upper end surface of the lower bush 213. This allows the rotor magnet 212 and the lower bush 213 to be fixed together with the adhesive.

[0045] Here, if the upper end surface of the lower bushing 213 is flat, the adhesive tends to flow in the radial direction from the upper end surface of the lower bushing 213. Therefore, the amount of adhesive present between the rotor magnet 212 and the lower bushing 213 in the axial direction is reduced.

[0046] 4, in this embodiment, the radial inner edge 2131 of the lower bush 213 is recessed downward from the upper end surface of the lower bush 213. In this configuration, a ring-shaped recess is formed by the radial outer surface of the shaft 211 and the radial inner edge 2131 of the lower bush 213. As a result, the adhesive flowing downward on the radial outer surface of the shaft 211 accumulates in the radial inner edge 2131. As a result, the shaft 211 and the lower bush 213 can be firmly fixed by the adhesive.

[0047] Further, a radial outer edge 2132 of the lower bush 213 is recessed downwardly from an upper end surface of the lower bush 213. Here, in order to fix the magnet cover 2120 to the radial outer surface of the rotor magnet 212, an adhesive is applied to the radial outer surface of the rotor magnet 212. The adhesive applied to the radial outer surface of the rotor magnet 212 flows downward along the radial outer surface of the rotor magnet 212 and accumulates at the radial outer edge 2132 of the lower bush 213. As a result, the fixation between the rotor magnet 212 and the magnet cover 2120 by the adhesive can be strengthened.

[0048] <5. Fixing the housing and stator> In this embodiment, as shown in Fig. 3 and Fig. 5, the second housing 32 has a lower cylinder portion 321. The lower cylinder portion 321 is cylindrical and centered on a central axis CA. The second holding portion 32a is connected to the lower cylinder portion 321. That is, the lower cylinder portion 321 has the second holding portion 32a at its radial center.

[0049] When the housing 3 and the stator 22 are fixed to each other, a portion of the stator 22 above the lower end is press-fitted into the inner cylindrical portion 311, and the lower end of the stator 22 is press-fitted into the lower cylindrical portion 321. When the stator 22 is press-fitted into both the inner cylindrical portion 311 and the lower cylindrical portion 321, the lower end 310 of the inner cylindrical portion 311 and the upper end 320 of the lower cylindrical portion 321 overlap in the radial direction.

[0050] Here, the stator vanes 313 are connected to the inner cylindrical portion 311. In this configuration, when attempting to overlap the upper end portion 320 of the lower cylindrical portion 321 with the lower end portion 310 of the inner cylindrical portion 311 from the radially outward side, measures such as making the stator vanes 313 smaller in the axial direction must be taken in order to ensure a space for overlapping the lower end portion 310 of the inner cylindrical portion 311 and the upper end portion 320 of the lower cylindrical portion 321.

[0051] Therefore, in this embodiment, the inner diameter of the lower end 310 of the inner cylindrical portion 311 is larger than that of the portion of the inner cylindrical portion 311 above the lower end 310. In other words, the lower end 310 of the inner cylindrical portion 311 is recessed radially outwardly more than the portion of the inner cylindrical portion 311 above the lower end 310 over the entire circumferential circumference. Note that the lower end 310 of the inner cylindrical portion 311 does not have a rib 3110 on its radially inner peripheral surface. Therefore, the lower end 310 of the inner cylindrical portion 311 and the stator 22 do not come into contact with each other, and a gap is provided between the lower end 310 of the inner cylindrical portion 311 and the stator 22 in the radial direction.

[0052] The upper end 320 of the lower cylindrical portion 321 is disposed in a radial gap between the lower end 310 of the inner cylindrical portion 311 and the stator 22. That is, the upper end 320 of the lower cylindrical portion 321 is disposed radially inward of the lower end 310 of the inner cylindrical portion 311. This eliminates the need to take measures such as reducing the size of the stator vane 313 in the axial direction.

[0053] <6. Usage example> FIG. 6 is a cross-sectional view that illustrates a hair dryer 1000 according to an embodiment.

[0054] The hair dryer 1000 includes a blower device 100. The hair dryer 1000 also includes a main body 1001, a handle 1002, and a heater 1003.

[0055] The main body 1001 is cylindrical. The handle 1002 is cylindrical. The upper end of the handle 1002 is connected to the trunk of the main body 1001. The interiors of the main body 1001 and the handle 1002 are in communication with each other. The heater 1003 is disposed inside the main body 1001. The blower 100 is disposed inside the handle 1002. Inside the handle 1002, the state of the blower 100 is upside down compared to the state shown in FIG. 2.

[0056] When the blower 100 is driven, air is taken into the inside of the handle part 1002 from the lower end part of the handle part 1002, generating an airflow. The airflow flows axially inside the main body part 1001 and is heated by the heater 1003. As a result, hot air is discharged from the main body part 1001.

[0057] In the hair dryer 1000 of this embodiment, the use of the air blowing device 100 makes it possible to suppress vibration and noise.

[0058] <7.Other> The embodiments of the present invention have been described above. Note that the scope of the present invention is not limited to the above-mentioned embodiments. The present invention can be implemented by adding various modifications within the scope of the gist of the invention. In addition, the above-mentioned embodiments can be combined in any suitable manner.

[0059] The present invention can have the following configurations (1) to (9).

[0060] (1) an impeller that can rotate around a central axis extending vertically; A motor that rotates the impeller; a housing that accommodates the impeller and the motor, The motor is A rotor rotatable about the central axis; a stator for rotating the rotor; The rotor is A shaft extending along the central axis; a rotor magnet fixed to a radially outer surface of the shaft; The impeller is fixed to a position on the radial outer surface of the shaft above a fixed position of the rotor magnet, The housing includes: a first bearing that rotatably supports the shaft at a position above a fixed position of the rotor magnet and below a fixed position of the impeller; a second bearing that rotatably supports the shaft at a position lower than a fixed position of the rotor magnet, a center of gravity of the impeller is located at a position overlapping with an upper end of the first bearing or located below the upper end of the first bearing when viewed from a radial direction;

[0061] (2) The blower device according to (1), wherein the center of gravity of the impeller is located at a position overlapping with a lower end of the first bearing or located above the lower end of the first bearing when viewed from a radial direction.

[0062] (3) The impeller is a base portion having a boss at a radial center portion thereof, the boss being fixed to a radial outer surface of the shaft; a cylindrical portion extending downward from a radially outer edge portion of the base portion; a plurality of rotor blades extending radially outward from a radially outer surface of the cylindrical portion and arranged in a circumferential direction; The center of gravity of the impeller is located radially inward of the cylindrical portion, The blower device according to (1) or (2), wherein an axial center of the first bearing is located above a lower end of the cylindrical portion.

[0063] (4) The blower device according to (3), wherein the boss protrudes upward from an upper surface of the base portion.

[0064] (5) The housing comprises: a first housing that holds the first bearing; a second housing that holds the second bearing, The first housing includes: an inner cylindrical portion having a cylindrical shape centered on the central axis, covering the stator from the outside in the radial direction and holding the stator; an outer cylindrical portion having a cylindrical shape centered on the central axis, the outer cylindrical portion being disposed radially outward from the inner cylindrical portion at a distance therefrom, and forming an air flow passage between the outer cylindrical portion and the inner cylindrical portion in the radial direction; a stator blade disposed radially between the inner cylindrical portion and the outer cylindrical portion, The blower device according to any one of (1) to (4), wherein a lower end of the first bearing is positioned higher than an upper end of the stator blade.

[0065] (6) The rotor has an upper bush fixed to a radially outer surface of the shaft, The blower device according to any one of (1) to (5), wherein the upper bushing is disposed axially between the rotor magnet and the first bearing.

[0066] (7) The rotor has a lower bush fixed to a radially outer surface of the shaft, the lower bush is disposed below the rotor magnet, The rotor magnet is fixed to the radially outer surface of the shaft with an adhesive; The blower device according to any one of (1) to (6), wherein a radially inner edge portion of the lower bush is recessed downwardly relative to an upper end surface of the lower bush.

[0067] (8) The housing comprises: a first housing that holds the first bearing; a second housing that holds the second bearing, The first housing includes: an inner cylindrical portion having a cylindrical shape centered on the central axis, covering the stator from the outside in the radial direction and holding the stator; an outer cylindrical portion having a cylindrical shape centered on the central axis, the outer cylindrical portion being disposed radially outward from the inner cylindrical portion at a distance therefrom, and forming an air flow passage between the outer cylindrical portion and the inner cylindrical portion in the radial direction; a stator blade disposed radially between the inner cylindrical portion and the outer cylindrical portion, A lower end portion of the inner cylindrical portion has an inner diameter larger than a portion of the inner cylindrical portion above the lower end portion, The second housing has a cylindrical lower cylinder portion centered on the central axis, The blower device according to any one of (1) to (7), wherein an upper end portion of the lower cylindrical portion is disposed radially inward of a lower end portion of the inner cylindrical portion.

[0068] (9) A hair dryer equipped with a blower device according to any one of (1) to (8). [Industrial Applicability]

[0069] The present invention can be used, for example, in an air blower mounted on a hair dryer or the like. [Explanation of symbols]

[0070] 1 Impeller 2 Motors 3. Housing 11 Base 12 Cylinder part 13 Moving blade 21 Rotor 22 Stator 31 1st Housing 32 Second Housing 100 Blower 110 Boss 211 Shaft 212 Rotor magnet 213 Lower Bush 214 Upper Bush 301 First bearing 302 No. 2 bearing 310 Lower end 311 Inner cylinder part 312 Outer cylinder part 313 Stator blade 320 Upper end 321 Lower cylinder part 1000 Hair Dryer 2131 Radial inner edge CA center axis P Center of gravity position

Claims

1. An impeller that can rotate around a central axis that extends vertically; A motor that rotates the impeller; a housing that accommodates the impeller and the motor, The motor is A rotor rotatable about the central axis; a stator for rotating the rotor; The rotor is A shaft extending along the central axis; a rotor magnet fixed to a radially outer surface of the shaft; The impeller is fixed to a position on the radial outer surface of the shaft above a fixed position of the rotor magnet, The housing includes: a first bearing that rotatably supports the shaft at a position above a fixed position of the rotor magnet and below a fixed position of the impeller; a second bearing that rotatably supports the shaft at a position lower than a fixed position of the rotor magnet, A blower device, wherein a center of gravity of the impeller is located at a position overlapping with an upper end of the first bearing or at a position lower than the upper end of the first bearing when viewed from a radial direction.

2. The blower device according to claim 1 , wherein a center of gravity of the impeller is located at a position overlapping with a lower end of the first bearing or located above the lower end of the first bearing when viewed from a radial direction.

3. The impeller is a base portion having a boss at a radial center portion thereof, the boss being fixed to a radial outer surface of the shaft; a cylindrical portion extending downward from a radially outer edge portion of the base portion; a plurality of rotor blades extending radially outward from a radially outer surface of the cylindrical portion and arranged in a circumferential direction; The center of gravity of the impeller is located radially inward of the cylindrical portion, The blower device according to claim 1 , wherein an axial center of the first bearing is located above a lower end of the cylindrical portion.

4. The blower device according to claim 3 , wherein the boss protrudes upward from an upper surface of the base portion.

5. The housing includes: a first housing that holds the first bearing; a second housing that holds the second bearing, The first housing includes: an inner cylindrical portion having a cylindrical shape centered on the central axis, covering the stator from the outside in the radial direction and holding the stator; an outer cylindrical portion having a cylindrical shape centered on the central axis, the outer cylindrical portion being disposed radially outward from the inner cylindrical portion at a distance therefrom, and forming an air flow passage between the outer cylindrical portion and the inner cylindrical portion in the radial direction; a stator blade disposed radially between the inner cylindrical portion and the outer cylindrical portion, The blower device according to claim 1 , wherein a lower end of the first bearing is located higher than an upper end of the stator blade.

6. The rotor has an upper bushing fixed to a radially outer surface of the shaft, The blower device according to claim 1 , wherein the upper bushing is disposed axially between the rotor magnet and the first bearing.

7. The rotor has a lower bushing fixed to a radially outer surface of the shaft, the lower bush is disposed below the rotor magnet, The rotor magnet is fixed to the radially outer surface of the shaft with an adhesive; The blower device according to claim 1 , wherein a radially inner edge portion of the lower bush is recessed downwardly below an upper end surface of the lower bush.

8. The housing includes: a first housing that holds the first bearing; a second housing that holds the second bearing, The first housing includes: an inner cylindrical portion having a cylindrical shape centered on the central axis, covering the stator from the outside in the radial direction and holding the stator; an outer cylindrical portion having a cylindrical shape centered on the central axis, the outer cylindrical portion being disposed radially outward from the inner cylindrical portion at a distance therefrom, and forming an air flow passage between the outer cylindrical portion and the inner cylindrical portion in the radial direction; a stator blade disposed radially between the inner cylindrical portion and the outer cylindrical portion, A lower end portion of the inner cylindrical portion has an inner diameter larger than a portion of the inner cylindrical portion above the lower end portion, The second housing has a cylindrical lower cylinder portion centered on the central axis, The blower device according to claim 1 , wherein an upper end portion of the lower cylindrical portion is disposed radially inward of a lower end portion of the inner cylindrical portion.

9. A hair dryer comprising the blower device according to claim 1.

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