JP2019060323A - Axial fan - Google Patents

Abstract

To provide an axial fan including an impeller which can stably rotate even if a range of an environmental temperature during driving is wide.SOLUTION: An axial fan includes: a rotor part having a shaft disposed along a center axis extending vertically; a stator part which is disposed facing a rotor part in a radial direction; and an impeller hub which is fixed to the rotor part and can integrally rotate with the rotor part. The impeller hub includes: a hub top plate part which is an injection molding item and extends in a direction perpendicular to an axial direction; a cylindrical hub cylinder part extending from an outer edge of the hub top plate part in an axially downward direction; multiple blades aligned in a circumferential direction on an outer surface of the hub cylinder part; and an inner fixing part disposed at the radial inner side of the hub cylinder part. The rotor part includes a cylindrical rotor cylinder part extending in the axial direction. The inner fixing part has first areas, each of which is formed with a weld located on a radial inner surface and faces an outer surface of the rotor cylinder part through a gap in the radial direction; and second areas, each of which contacts with at least a part of the outer surface of the rotor cylinder part.SELECTED DRAWING: Figure 10

Description

  The present invention relates to axial fans.

  A conventional fan is disclosed in Patent Document 1. The fan has an impeller attached to a rotor yoke. The impeller includes an impeller cup having a frusto-conical cylindrical peripheral wall portion, and a plurality of vanes arranged in an annular shape protrude from an outer peripheral surface of a common wall portion of the impeller cup. And an annular member is concentrically integrally formed inside the peripheral wall part of an impeller cup. A plurality of support members are formed in the circumferential direction between the impeller cup peripheral wall inner peripheral surface and the annular member outer peripheral surface. Furthermore, a plurality of ribs are provided to project radially inward of the annular member. When the rotor yoke is pressed into the impeller cup, radially outward stress is applied to the ribs. As a result, the radially outer press-in stress that acts on the rib at the time of press-in is absorbed as a circumferential force by the annular member to reduce the load applied to the impeller cup.

JP, 2008-069672, A

  In recent years, a high air volume fan motor capable of continuous driving at high temperature has been required. At high temperatures, the bending elastic modulus tends to decrease. Therefore, in order to suppress the deformation of the impeller blade, it is preferable to select a material having a high bending elastic modulus. In addition, since it is necessary to rotate the fan motor at high speed due to the demand of high air volume, the impeller cup and the rotor yoke are firmly fixed in order to maintain the balance of the impeller even when rotating at high speed under high temperature. Need to be On the other hand, when the impeller cup is formed of a material having a high flexural modulus, when the environmental temperature changes from high temperature to low temperature, the thermal stress due to the thermal expansion difference between the impeller cup and the rotor yoke tends to be larger. In addition, when the environmental temperature changes from low temperature to high temperature, the fixing strength between the impeller cup and the rotor yoke may be reduced due to the thermal expansion difference between the impeller cup and the rotor yoke. Therefore, even when the environmental temperature changes, it is required to suppress the increase in thermal stress acting on the impeller and the rotor yoke, and realize a strong fixation, so that a fan motor that can be stably and continuously driven is desired. ing.

  Therefore, an object of the present invention is to provide an axial flow fan provided with an impeller that can stably rotate even when the range of driving environmental temperature is wide.

  An exemplary axial flow fan according to the present invention comprises a rotor portion having a shaft disposed along a vertically extending central axis, a stator portion disposed radially opposite to the rotor portion, and the rotor portion. An impeller hub fixed and integrally rotatable with the rotor portion, the impeller hub being an injection-molded article, a hub top plate portion extending in a direction orthogonal to the axial direction, and an outer edge of the hub top plate portion A cylindrical hub cylinder extending axially downward from the shaft, a plurality of blades circumferentially arranged on the outer surface of the hub cylinder, and an inner fixing part arranged radially inward of the hub cylinder; And the rotor portion includes an axially extending cylindrical rotor cylinder portion, and the inner fixing portion has a weld formed on the inner surface in the radial direction, and a gap in the radial direction from the outer surface of the rotor cylinder portion. Opposing first regions, and the rotor It has a second region in contact with at least a portion of the outer surface of the part, the.

  According to the exemplary axial flow fan of the present invention, stable rotation is possible even when the range of driving environmental temperature is wide.

FIG. 1 is a perspective view showing an example of an axial flow fan according to the present invention. FIG. 2 is a plan view of the axial flow fan shown in FIG. FIG. 3 is a longitudinal sectional view of the axial flow fan shown in FIG. FIG. 4 is a perspective view of the housing. FIG. 5 is a perspective view of the stator portion. FIG. 6 is a perspective view of a rotor yoke. FIG. 7 is a perspective view of the impeller. FIG. 8 is a perspective view of the lower side of the impeller shown in FIG. FIG. 9 is a plan view of the impeller shown in FIG. FIG. 10 is a bottom view of the impeller shown in FIG. FIG. 11 is a plan view showing a state in which the blades attached to the impeller hub are expanded in the circumferential direction. FIG. 12 is a view in which circumferentially deployed wings, in which circumferential cross sections at different positions in the radial direction of the vanes are developed in the circumferential direction, are overlapped and displayed. FIG. 13 is a schematic bottom view showing the arrangement of the inner fixing portion. FIG. 14 is a longitudinal sectional view of an impeller used in another example of the axial flow fan according to the present invention. FIG. 15 is a schematic bottom view of a first wall provided to the impeller shown in FIG. FIG. 16 is a bottom view of an impeller used in another example of the axial flow fan according to the present invention.

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. In the present specification, in the axial fan A, a direction parallel to the central axis C1 of the axial fan A is “axial direction”, a direction orthogonal to the central axis C1 of the axial fan A is “radial direction”, the axis A direction along an arc centered on the central axis C1 of the flow fan A is taken as a "circumferential direction". Further, in the present specification, in the axial flow fan A, the shape and the positional relationship of each part will be described with the axial direction as the vertical direction and the intake port 16 side of the housing 10 above the impeller 40. The vertical direction is a name used merely for the purpose of explanation, and does not limit the positional relationship and direction of the axial flow fan A in use. Also, “upstream” and “downstream” indicate upstream and downstream of the flow direction of the air flow generated when the impeller 40 is rotated, respectively.

First Embodiment
<1. Configuration of axial fan A>
FIG. 1 is a perspective view showing an example of an axial flow fan according to the present invention. FIG. 2 is a plan view of the axial flow fan shown in FIG. FIG. 3 is a longitudinal sectional view of the axial flow fan shown in FIG.

  As shown in FIGS. 1 to 3, the axial flow fan A according to the present embodiment includes a housing 10, a stator portion 20, a rotor portion 30, and an impeller 40. The stator portion 20 is fixed to the housing 10. The rotor portion 30 is rotatable with respect to the stator portion 20, and is disposed radially outward of the stator portion 20 with a gap. The impeller 40 is attached to the rotor unit 30.

<1.1 Configuration of Housing 10>
The housing 10 will be described with reference to the new drawing. FIG. 4 is a perspective view of the housing. In addition, in the perspective view shown in FIG. 4, the shaft 31 which the rotor part 30 mentions later is also displayed.

  The housing 10 includes a wind tunnel portion 11, a base portion 12, a vane 13, a bearing holding cylindrical portion 14, and a flange portion 15. The wind tunnel portion 11 has a cylindrical inner surface extending along the central axis C1. The wind tunnel portion 11 rotates the impeller 40 inside. The wind tunnel portion 11 is a guide for guiding the air flow generated by the rotation of the impeller 40 along the central axis C1. The axial direction upper end of the wind tunnel portion 11 is an inlet 16, and the axial lower end is an exhaust port 17. That is, as the impeller 40 rotates, air is sucked from the intake port 16, and the air flow accelerated or pressurized by the impeller 40 is discharged from the exhaust port 17.

  The flange portion 15 extends radially outward from each of both axial end portions of the wind tunnel portion 11. The flange portion 15 is provided with a mounting hole 151 penetrating in the axial direction. The mounting holes 151 are used when mounting the axial fan A to the device. That is, an attachment screw, a boss or the like provided in the device is inserted into the attachment hole 151, and the axial flow fan A is fixed to the device by fixing the flange portion 15 to the device. In addition, although the flange part 15 is square shape as shown to FIG. 1, FIG. 2, FIG. 4 etc., polygons, such as a circle | round | yen, a rectangle, and a hexagon, may be sufficient. The axial flow fan A can be shaped according to the shape of the mounting position of the axial flow fan A of the apparatus to which it is attached.

  The base portion 12 holds the stator portion 20. The base portion 12 has a base through hole 120 penetrating in the axial direction at the central portion (see FIG. 3), and is provided with a cylindrical tube holding portion 121 projecting axially upward above the side edge portion of the base through hole 120 .

  The base portion 12 is disposed at the lower end portion of the wind tunnel portion 11 in the axial direction, that is, at the downstream end portion of the wind tunnel portion 11 in the flow direction of the air flow. And it arrange | positions inside the wind tunnel part 11 in radial direction. The wind tunnel portion 11 and the base portion 12 are arranged with a gap in the radial direction. A plurality of stator blades 13 are disposed in the circumferential direction in the gap between the wind tunnel portion 11 and the base portion 12. The vanes 13 are connected to the wind tunnel 11 and the base 12. In other words, the base portion 12 is held by the wind tunnel portion 11 via the vanes 13. The stationary blades 13 rectify the air flow generated by the rotation of the impeller 40 into an axially symmetric flow about the central axis C1. Therefore, the plurality of stator blades 13 are arranged at equal intervals in the circumferential direction. Although the base portion 12 is integrally formed with the housing 10, the base portion 12 may be formed separately from the housing 10.

  The bearing holding cylinder portion 14 is cylindrical, and the stator portion 20 is fixed to the outer peripheral surface. The bearing holding cylinder portion 14 is fixed to the cylinder holding portion 121 of the base portion 12 along the central axis C1. The bearing holding cylinder portion 14 holds the first bearing 141 and the second bearing 142 on the inner peripheral surfaces of the upper end portion and the lower end portion in the axial direction. As shown in FIG. 3, the first bearing 141 is disposed at the upper end in the axial direction, and the second bearing 142 is disposed at the lower end in the axial direction. The first bearing 141 and the second bearing 142 rotatably support a later-described shaft 31 of the rotor unit 30.

  The bearing holding cylinder portion 14 is fixed to the cylinder holding portion 121 of the base portion 12 so as to overlap the center with the central axis C1. Therefore, the center of the stator portion 20 fixed to the outer peripheral surface of the bearing holding portion 14 coincides with the central axis C1. Therefore, the center of the shaft 31 rotatably supported by the bearing holding cylindrical portion 14 via the first bearing 141 and the second bearing 142 also coincides with the central axis C1. That is, the centers of the stator portion 20 and the rotor portion 30 coincide with the central axis C1. Thereby, the radial direction outer surface of the teeth part 212 which the stator part 20 mentioned later mentions, and the inner skin of the rotor magnet 34 which the rotor part 30 mentions later mentions a predetermined interval, and counters in the diameter direction.

  The first bearing 141 and the second bearing 142 are ball bearings. Then, the shaft 31 is fixed to the inner ring of the first bearing 141 and the second bearing 142. The fixing method of the shaft 31 and the inner ring of the first bearing 141 and the second bearing 142 may be, for example, adhesive insertion or press-fitting, but is not limited thereto. The first bearing 141 and the second bearing 142 are not limited to ball bearings.

<1.2 Configuration of Stator Unit 20>
The details of the stator unit 20 will be described with reference to the new drawings. FIG. 5 is a perspective view of the stator portion. As shown in FIG. 3, FIG. 5, etc., the stator unit 20 includes a stator core 21, an insulator 22, and a coil 23. The stator core 21 has conductivity. The stator core 21 includes an annular core back portion 211 and teeth portions 212. The core back portion 211 has an annular shape extending in the axial direction. The teeth 212 project radially inward from the inner circumferential surface of the core back portion 211. The stator core 21 includes a plurality of teeth 212. The plurality of teeth 212 are arranged at equal intervals in the circumferential direction.

<1.2.1 Configuration of Stator Core 21>
The stator core 21 may have a structure in which electromagnetic steel sheets are laminated, or may be a single member formed by firing, casting or the like of powder. In addition, stator core 21 may be configured to be divisible into divided cores including one tooth portion 212, or may be configured to be formed by winding a band-shaped member. The radial center of the stator core 21 penetrates in the axial direction.

<1.2.2 Configuration of Insulator 22>
The insulator 22 is a molded body of resin. The insulator 22 covers at least the entire teeth portion 212 of the stator core 21. A conductive wire is wound around the tooth portion 212 covered by the insulator 22 to form the coil 23. The stator core 21 and the coil 23 are insulated by the insulator 22. In the present embodiment, the insulator 22 is a resin molded body, but is not limited to this. The structure which can insulate stator core 21 and coil 23 can be widely adopted.

<1.2.3 Configuration of Coil 23>
The coils 23 are disposed at each of the teeth portions 212 of the stator core 21. The plurality of coils 23 provided in the stator 3 are divided into three systems (hereinafter referred to as three phases) according to the timing at which current is supplied. These three phases are respectively referred to as a U phase, a V phase, and a W phase. That is, the stator 1 includes the same number of U-phase coils, V-phase coils, and W-phase coils. In the following description, the coils of each phase are collectively described simply as the coil 23.

<1.2.4 Mounting of Stator Unit 20>
The stator portion 20 is fixed to the bearing holding cylindrical portion 14 by bringing the inner peripheral surface of the penetrating portion of the stator core 21 into contact with the outer peripheral surface of the bearing holding cylindrical portion 14. In addition, although the press-fit, adhesion | attachment etc. can be mentioned, the fixing method of the stator core 21 and the bearing holding | maintenance cylinder part 14 is not limited to these. It is possible to widely adopt a method capable of firmly fixing the stator core 21 to the bearing holding cylinder portion 14.

  By fixing the stator core 21 to the bearing holding cylindrical portion 14, the stator portion 20 is fixed to the base portion 12, that is, to the inside of the wind tunnel portion 11 of the housing 10. Thus, the teeth 212 are equally spaced around the central axis C1.

<1.3 Configuration of Rotor Unit 30>
As shown in FIG. 3, the rotor unit 30 includes a shaft 31, a rotor yoke 33, and a rotor magnet 34. The shaft 31 is cylindrical. The shaft 31 is disposed along the axial direction along the central axis C1. The rotor yoke 33 is made of metal.

<1.3.1 Configuration of Rotor Yoke 33>
The details of the rotor yoke 33 will be described with reference to the new drawings. FIG. 6 is a perspective view of a rotor yoke. As shown in FIG. 6, the rotor yoke 33 includes a rotor top plate portion 331 and a rotor cylinder portion 332. The rotor top plate portion 331 is expanded in the radial direction, and has a disk shape when viewed in the axial direction. At the center of the rotor top plate portion 331, a central through hole 333 penetrating in the axial direction is formed. Further, the rotor top plate portion 331 is provided with a plurality of, in this case, four positioning holes 334 penetrating in the axial direction. In the positioning hole 334, a second boss 415, which will be described later, of the impeller 40 is inserted.

  The rotor cylindrical portion 332 has a cylindrical shape extending axially downward from the outer peripheral edge of the rotor top plate 331. The rotor cylindrical portion 332 is fixed to the inner fixing portion 43 of the impeller 40 described later by press fitting. The connecting portion 32 is inserted into the central through hole 333.

<1.3.2 Configuration of Coupling Unit 32>
The connecting portion 32 connects and fixes the rotor top plate portion 331 and the shaft 31. The connecting portion 32 includes a connecting hole 321, a yoke fixing portion 322, and a connecting cylindrical portion 323. The connecting cylinder portion 323 has a tubular shape extending in the axial direction. The yoke fixing portion 322 is disposed at the lower end in the axial direction of the connecting cylindrical portion 323. The connection hole 321 penetrates the connection cylindrical portion 323 in the axial direction.

  The axial upper end of the shaft 31 is inserted into the connection hole 321. The axial direction upper end portion of the shaft 31 is press-fit into the connection hole 321 and fixed to the connection portion 32. The yoke fixing portion 322 is inserted into the central through hole 333 of the rotor yoke 33. The yoke fixing portion 322 has a cylindrical outer surface, and is fixed in contact with the inner surface of the central through hole 333. The connecting cylindrical portion 323 is inserted into an axial through hole 414 of the impeller 40, which will be described later, and is fixed inside the axial through hole 414. For example, bonding, welding, and the like can be mentioned as a method of fixing the connection cylindrical portion 323 and the shaft through hole 414, but it is not limited thereto.

  The connecting portion 32 fixes the shaft 31 and the impeller 40, and the shaft 31 and the rotor yoke 33 to each other. That is, the impeller 40 and the rotor yoke 33 are fixed to the shaft 31 by the connecting portion 32.

<1.3.3 Configuration of Rotor Magnet 34>
The rotor magnet 34 has a cylindrical shape in which the N pole and the S pole are alternately magnetized in the circumferential direction. The rotor magnet 34 is fixed with the outer peripheral surface in contact with the inner peripheral surface of the rotor yoke 33. The rotor magnet 34 may be integrally molded of resin containing magnetic powder, or may be formed by arranging a plurality of magnets in the circumferential direction and fixing them with resin or the like. As a fixing method for fixing the rotor magnet 34 to the rotor yoke 33, press fitting, bonding, etc. may be mentioned, but it is not limited thereto. It is possible to widely adopt a method in which the magnet 34 can be firmly fixed to the rotor yoke 33.

<1.3.4 Mounting of the rotor unit 30>
The shaft 31 is rotatably mounted via the first bearing 141 and the second bearing 142 held by the bearing holding cylinder portion 14. Then, the rotor yoke 33 to which the rotor magnet 34 is fixed is fixed to the shaft 31 via the connecting portion 32. At this time, the radially inner peripheral surface of the rotor magnet 34 is radially opposed to the radially outer surface of the teeth portion 212 of the stator portion 20 fixed to the bearing holding cylindrical portion 14 with a gap. The base portion 12, the bearing holding cylindrical portion 14, the stator portion 20 and the rotor portion 30 constitute a so-called outer rotor type DC brushless motor in which the rotor portion 30 is disposed radially outside the stator portion 20. In the present embodiment, the base portion 12 is integrally formed with the housing 10, but the base portion 12 may be formed separately from the housing 10. In this case, a separately assembled motor may be attached to the housing 10.

  Then, in the rotor magnet 34, an attractive force or a repulsive force is generated by the magnetic flux generated by supplying an electric current to the coil of the stator unit 20. The rotor unit 30 rotates around the central axis C 1 with respect to the stator unit 20 by the attractive force or the repulsive force generated in the rotor magnet 34. Then, as the rotor unit 30 rotates, the impeller 40 fixed to the rotor unit 30 rotates around the central axis C1.

<1.4 Configuration of Impeller 40>
The details of the impeller 40 will be described with reference to the new drawings. FIG. 7 is a perspective view of the impeller. FIG. 8 is a perspective view of the lower side of the impeller shown in FIG. FIG. 9 is a plan view of the impeller shown in FIG. FIG. 10 is a bottom view of the impeller shown in FIG.

  As shown in FIGS. 7 to 10, the impeller 40 includes an impeller hub 41, a plurality of blades 42, and an inner fixing portion 43. The impeller 40 is formed by injection molding of resin.

<1.4.1 Configuration of Impeller Hub 41>
As shown in FIGS. 3, 7, 8, etc., the impeller hub 41 includes a hub top plate portion 411 and a hub cylinder portion 412. The hub top plate portion 411 has a disk shape that expands in the radial direction. The hub cylindrical portion 412 has a tubular shape extending axially downward from the radial outer edge of the hub top plate portion 411. The hub top plate portion 411 includes a first boss 413, an axial through hole 414, and a second boss 415. The axial through hole 414 is disposed at the axial center of the hub top plate 411 and penetrates the hub top 411 in the axial direction. The connecting cylindrical portion 323 of the connecting portion 32 is inserted into the shaft through hole 414 and fixed. That is, the shaft 31 is fixed to the shaft through hole 414 via the connecting cylinder portion 323.

  The first boss 413 and the second boss 415 project axially downward from the lower surface of the hub top plate 411 in the axial direction. The first boss 413 and the second boss 415 are integrally formed of the same member as the hub top plate 411. Here, four first bosses 413 are provided. The positioning hole 334 of the rotor yoke 33 is inserted into the first boss 413. Thus, the rotor yoke 33 is positioned in the circumferential direction with respect to the impeller hub 41.

  Further, the axial length of the second boss 415 is shorter than the length of the first boss 413. The upper surface of the rotor top plate portion 331 of the rotor yoke 33 is in contact with the axial lower surface of the second boss 415. That is, the rotor yoke 33 is positioned with respect to the impeller hub 41 in the axial direction by bringing the upper surface of the rotor top plate portion 331 into contact with the lower surface of the second boss 415 in the axial direction.

  As shown in FIGS. 7 and 9, a plurality of gate marks 45 are formed on the upper surface of the hub top plate portion 411 of the impeller hub 41. The gate marks 45 are marks formed in an injection port (gate) for injecting a resin provided in a mold (not shown) when the impeller hub 41 is subjected to injection molding of the resin. The four gate marks 45 are provided, and the four gate marks 45 are arranged at equal intervals in the circumferential direction around the central axis C1.

  When resin is injected into the mold from a plurality of gates, welds, which are joints of resin, are formed at circumferentially central portions of adjacent gates in the circumferential direction. That is, in the weld, a weld is formed in the circumferential direction central portion of adjacent gate marks 45 in the circumferential direction. The details of the weld will be described later.

<1.4.2 Configuration of Blade 42>
The plurality of blades 42 are circumferentially juxtaposed on the outer surface of the impeller hub 41. In the present embodiment, the blades 42 are arranged in parallel in a predetermined cycle in the circumferential direction on the outer surface of the hub portion 21 and integrally molded with the impeller hub 41. The upper portion of the blade 42 is disposed forward of the lower portion in the rotational direction Rd (see FIG. 3). The upper portion of the blade 42 is disposed forward in the rotational direction Rd with respect to the lower portion.

  Further details of the vanes 42 will be described with reference to the new drawings. FIG. 11 is a plan view showing a state in which the blades attached to the impeller hub are expanded in the circumferential direction.

  As shown in FIG. 11, the innermost in the axial direction of the blade 42 is taken as the innermost circumferential part 4201, and the outermost in the axial direction of the blade 42 is taken as the outermost part 4202. As shown in FIG. 11, the innermost circumferential portion 4201 has the same outer diameter as the outer surface of the impeller hub 42. Then, between the innermost circumferential portion 4201 and the outermost circumferential portion 4202 of the blade 42 in the radial direction, a first intermediate circumferential portion 4203 and a second intermediate circumferential portion 4204 are formed. The first intermediate circumferential portion 4203 and the second intermediate circumferential portion 4204 are positioned at equal intervals between the innermost circumferential portion 3201 and the outermost circumferential portion 4202. That is, the first intermediate circumferential portion 4203 is radially inside a line that divides the blade 42 into three equal parts in the radial direction. In addition, the second intermediate circumferential portion 4204 is radially outside of a line that equally divides the blade 42 in the radial direction.

  As shown in FIG. 11, the blades 42 are connected to the impeller hub 41 at the innermost circumferential portion 4201. On the other hand, on the radially outer side of the innermost circumferential portion 4201 of the blade 42, the front side in the rotational direction Rd has a portion located ahead of the foremost portion in the rotational direction Rd of the innermost circumferential portion 4201. These portions are not connected to the impeller hub 41 in the radial direction, and the strength is low. Therefore, when the impeller 40 rotates, the front side in the rotational direction Rd is likely to be deformed radially outward. Further, the radial length of the cross section cut by a plane including the central axis C1 on the rear side in the rotational direction Rd of the blade 42 is short, and the cross section coefficient is small. Therefore, the rear side of the rotational direction Rd of the blades 42 is also easily deformed radially outward due to the rotation of the impeller 40. Furthermore, since the air flow generated by the rotation of the impeller 40 is peeled off on the rear side in the rotational direction Rd of the blades 42, the stress is increased. Also from this point, the rear side of the rotational direction Rd of the blade 42 is easily deformed radially outward.

  When the blade 42 is cut at a cross section including the central axis C1 when the blade 42 rotates, the cross section coefficient increases as the radial length of the cross section increases. And the part of the blade 42 fixed in the radial direction with the impeller hub 41 is unlikely to be deformed in the radial direction. Using this, the shape of the blade 42 is determined.

  A method of determining the radial length of the blade 42 will be described with reference to the drawings. FIG. 12 is a view in which circumferentially deployed wings, in which circumferential cross sections at different positions in the radial direction of the vanes are developed in the circumferential direction, are overlapped and displayed.

  FIG. 12 is a diagram in which the shapes of the innermost circumferential portion 4201, the outermost circumferential portion 4202, the first intermediate circumferential portion 4203 and the second intermediate circumferential portion 4204 of the blade 42 are expanded in the circumferential direction. 11 and 12 is based on the upstream end of the innermost circumferential portion 4201 in the rotational direction Rd of the impeller 40. As shown in FIG. 12, a shape developed in the circumferential direction of the shape of the innermost circumferential portion 4201 of the blade 42 is referred to as an inner circumferential development blade 421. Similarly, the shape developed in the circumferential direction of the shape of the outermost periphery 4202 of the blade 42 is developed into an outer circumferential deployment wing 422, and a first intermediate circumferential portion 4203 and a second intermediate circumferential portion 4204 of the vane 42 as a first intermediate circumferential direction deployment. The wing 423 and the second intermediate circumferential deployment wing 424 are used.

  The blades 42 are connected to the impeller hub 41 on the rear side of the rotational direction Rd with respect to the foremost part of the inner circumferential development wing 421 in the rotational direction Rd. The radial width of the blade 42 is the portion where the inner circumferential development wing 421, the outer circumferential development wing 422, the first intermediate circumferential development wing 423, and the second intermediate circumferential development wing 424 overlap in the radial direction. Wide, ie difficult to deform. Therefore, a portion where the inner circumferential development wing 421, the outer circumferential development wing 422, the first intermediate circumferential development wing 423, and the second intermediate circumferential development wing 424 of the blades 42 overlap with each other is referred to as a first portion 425. Then, the first portion 425 of the blade 42 is determined by returning the first portion 425, which is set by overlapping the circumferential development views, from the development view in the circumferential direction (see FIG. 2, FIG. 11, etc.). In FIGS. 2 and 11, both ends in the rotational direction of the first portion 425 are indicated by broken lines.

  And in the blade | wing 42, it is hard to deform | transform the 1st part 425 to the radial direction outer side at the time of rotation. As shown in FIG. 3, when the impeller 40 is housed in the wind tunnel portion 11 of the housing 10, the radially outermost portion (the outermost diameter portion) of the first portion 425 of the blade 42 and the inner surface of the wind tunnel portion 11 The gap Gp1 is smaller than the gap Gp2 between the outermost diameter portion on the front side in the rotational direction of the first portion 425 and the inner surface of the air channel portion. In addition, the gap Gp1 is smaller than the gap Gp3 between the outermost diameter portion on the rear side in the rotational direction of the first portion 425 and the inner surface of the air channel portion. That is, the outermost diameter portion of the blade 42 has the shortest distance to the inner surface of the wind tunnel portion 11 in at least a part of the first portion 425.

  Then, the distance between the outermost diameter portion of the blade 42 and the inner surface of the air channel 11 gradually becomes longer toward the front in the rotational direction than the first portion 425. Similarly, the distance between the outermost diameter portion of the blade 42 and the inner surface of the wind tunnel portion 11 gradually increases toward the rear in the rotational direction with respect to the first portion 425.

  With such a configuration, when the impeller 40 rotates, the gap between the radial outer edge of the blade 42 of the impeller 40 and the inner surface of the wind tunnel 11 can be optimized, and the blowing efficiency by the rotation of the impeller 40 can be reduced. It is possible to raise. In addition, since the rotation direction rear side of the blade | wing 42 is a part which air flow peels, big stress acts compared with another part. Therefore, it is preferable that the radial distance between the outermost diameter portion and the inner surface of the wind tunnel portion 11 be the longest at the end portion on the rotational direction rear side of the outermost diameter portion of the blade 42.

  As shown in FIG. 3, the area of the first portion 425 when the blade 42 is viewed in the axial direction is the sum of the area of the region 426 forward of the first portion 425 and the region 427 behind the rotation direction. Is also made smaller. By forming in this manner, the gap between the outermost diameter portion of the blade 42 and the inner surface of the wind tunnel portion 11 can be adjusted more optimally.

  In addition, in this embodiment, as a shape of the intermediate | middle part of the radial direction of the blade | wing 42, although two places (1st intermediate peripheral part 4203 and 2nd intermediate peripheral part 4204) are employ | adopted, it is not limited to this. It may be at least one, or three or more. Further, in the first portion 425, the circumferential length of the portion at which the radial distance between the outermost diameter portion of the blade 42 and the inner surface of the wind tunnel portion 11 is shortest is the circumferential length of the outer circumferential development wing 422 Preferably greater than half of

<1.4.3 Configuration of Inner Fixing Portion 43>
The details of the inner fixing portion 43 will be described with reference to the new drawings. FIG. 13 is a schematic bottom view showing the arrangement of the inner fixing portion. As shown in FIGS. 8, 10, and 13, the inner fixing portion 43 is disposed radially inward of the hub cylindrical portion 412. The inner fixing portions 43 each include wall portions 430 aligned in the circumferential direction. The wall portion 430 extends axially downward from the lower surface of the hub top plate portion 411. The wall 430 is formed integrally with the hub top plate 411. In addition, the inner fixing portion 43 may have a tubular shape extending in the axial direction.

  The wall 430 includes four first walls 431 and four second walls 432. The first wall portion 431 has, on the radial inner surface, a thick portion 433 whose distance from the central axis is shorter than other portions of the radial inner surface of the first wall portion 431. The four first wall portions 431 are arranged at equal intervals in the circumferential direction. The rotor cylindrical portion 332 is pressed into contact with the inner fixing portion 43, that is, the wall portion 430. As shown in FIG. 13, the radially inner surface of the thick portion 433 is in contact with the outer surface of the rotor cylindrical portion 332. The rotor cylindrical portion 33 is pressed into contact with the thick portion 433. In the thick portion 433, the distance from the central axis C <b> 1 continuously increases as going from the circumferential center to the circumferential outer side.

  In addition, the second wall portions 432 are disposed between the adjacent first wall portions 431 in the circumferential direction. The four second wall portions 432 are also arranged at equal intervals in the circumferential direction. That is, in the circumferential direction, the first wall portions 431 and the second wall portions 432 are alternately arranged at equal intervals.

  A weld 434 is formed on the radial inner surface of the second wall portion 432 in the central portion in the circumferential direction. The weld 434 is lower in strength than other portions because it is a joint portion of the resin flowing in from a different direction. Therefore, when the rotor cylindrical portion 332 is press-fit into the inner fixing portion 43, that is, the wall portion 430, stress is concentrated on the weld 434 at the time of press-fitting or when the impeller 40 rotates. In order to suppress, it opposes the outer surface of the rotor cylindrical portion 332 via a gap.

  In the inner fixing portion 43, a portion where the weld 434 is formed on the inner surface in the radial direction becomes a first region 4301 opposed to the outer surface of the rotor cylindrical portion 332 in the radial direction with a gap. In addition, a portion where the outer surface of the rotor cylindrical portion 332 contacts is a second region 4302.

  The weld 434 is formed at the central portion of the adjacent gate marks 45. The second area 4302 is disposed between the first area 4301 in the circumferential direction. Therefore, the second region 4302 is disposed in the region between the welds 434 adjacent in the circumferential direction. That is, at least a part of the outer surface of rotor cylindrical portion 332 has a central portion of gate mark 45 and gate mark 45 adjacent to one side in the circumferential direction, and gate mark 45 and gate mark 45 adjacent to the other side in the circumferential direction. It contacts the inner surface of the inner fixed portion 43 (4301) located in the area between the central portion. The first wall portion 431 is located on an imaginary line VL connecting the gate mark 45 and the central axis C1 (see FIGS. 3 and 13). In other words, the inner side is located in the region between the central portion of the gate mark 45 and the gate mark 45 adjacent to one circumferential side and the central portion of the gate mark 45 and the gate mark 45 adjacent to the other circumferential side. It can be said to be in contact with the inner surface of the fixed part.

  As shown in FIGS. 3, 8 and 10, in the radial direction, between the hub cylindrical portion 412 and the wall portion 430, there is provided a recess 46 which is recessed axially upward from the lower end portion in the axial direction. The wall portion 430 is connected to the inner surface in the radial direction of the hub cylindrical portion 412 at a connection portion 44 disposed in the recess 46. The connecting portion 44 extends in the axial direction. The axial length of the recess 46 is shorter than the axial length of the impeller hub 41.

  As shown in FIG. 10, both ends in the circumferential direction of the first wall portion 431 are connected to the hub cylindrical portion 412 at the connection portion 44. And the center part of the circumferential direction of the 1st wall part 431 is thick part. The circumferentially central portion of the first wall portion 431 and the hub cylindrical portion 412 face each other in the radial direction via the recess 46. By being formed in this manner, the first wall portion 431 can be flexed. Thereby, it is possible to disperse the stress when the rotor cylindrical portion 332 is press-fitted. Further, the first wall portion 431 is a resin, and the rotor cylindrical portion 332 is made of metal. Therefore, when the temperature of the first wall portion 431 and the rotor cylindrical portion 332 rises, the first wall portion 431 has a thermal expansion larger than that of the rotor cylindrical portion 332. By providing the recessed portion 46 between the radially outer side of the circumferential center portion of the first wall portion 431 and the hub cylindrical portion 412, the first wall portion 431 is deformed radially outward. Thus, even if a thermal expansion difference occurs at the contact portion between the first wall portion 431 and the rotor cylindrical portion 332, the increase in stress is suppressed.

  Further, the radially outer side of the circumferential center portion of the second wall portion 432 is connected to the radial inner surface of the hub cylindrical portion 412 by the connection portion 44. The second wall portion 432 is connected by one connection portion 44. Also, as described above, the weld 434 is formed at the circumferential center of the second wall 432. By connecting to the radial inner surface of the hub cylindrical portion 414 via the connection portion 44 at the portion where the weld 434 is formed, the strength of the portion where the weld 434 is formed can be enhanced. In addition, even when a difference in thermal expansion between the second wall portion 432 and the rotor cylindrical portion 332 occurs, the second wall portion 432 and the rotor cylindrical portion 332 are disposed with a gap in the radial direction, so that the stress rises. Is suppressed.

  By using the above configuration, even when the axial flow fan A is driven than when the rotor yoke 33 is press-fit into the impeller hub 41, the temperatures of the inner fixing portion 43 (wall portion 430) and the rotor cylindrical portion 332 rise. , And increase in stress of the inner fixing portion 43 (the wall portion 430) can be suppressed. Thereby, it is possible to suppress the fluctuation of the internal stress due to the temperature change at the time of manufacturing (press-in) and at the time of driving, and to rotate the impeller 40 stably.

Second Embodiment
Another example of the axial flow fan according to the present invention will be described with reference to the drawings. FIG. 14 is a longitudinal sectional view of an impeller used in another example of the axial flow fan according to the present invention. FIG. 15 is a schematic bottom view of a first wall provided to the impeller shown in FIG. The axial flow fan of the second embodiment has the same configuration as the axial flow fan A described in the first embodiment except that the configuration of the impeller 40B is different. Therefore, in the second embodiment, detailed descriptions other than the impeller 40B will be omitted.

  As shown in FIG. 14, the impeller 40 </ b> B has a configuration in which the wall portion 430 of the impeller 40 in the first embodiment is replaced with a wall portion 47. The wall 47 includes a first wall 471 and a second wall 472. The second wall 472 has substantially the same configuration as the second wall 432 of the impeller 40. That is, the second wall portion 472 opposes the rotor cylindrical portion 332 in the radial direction with a gap.

  As shown in FIG. 14 and FIG. 15, the first wall portion 471 includes a rib 473 projecting radially inward at a circumferential center portion of the inner surface in the radial direction. In the first wall portion 471, the rib 473 is a thick portion. Therefore, when the rotor yoke 33 is press-fit into the impeller hub 41 of the impeller 40B, the radially outer surface of the rotor cylindrical portion 332 contacts the radially inner surface of the rib 473.

  Further, as shown in FIG. 14, a gap is provided between the rib 473 and the lower surface in the axial direction of the rotor top plate portion 331. In a region of the hub top plate 411 opposite to the rib 473 in the axial direction, a through hole 48 penetrating in the axial direction is provided.

  By providing a gap between the upper end of the rib 473 and the rotor top plate portion 331, when the rotor yoke 33 is press-fit into the impeller hub 41, the press-fit stress is not transmitted to the hub top plate portion 412 of the impeller hub 41. Thereby, the deformation of the impeller hub 41 can be suppressed.

  Further, by forming the through holes 48, when the gap between the rib 473 and the rotor top plate portion 331 is formed by injection molding of resin, it can be formed by an insert (mold) which is drawn out in the axial direction. Therefore, the configuration of the mold can be simplified.

  The other features are the same as in the first embodiment.

Third Embodiment
Another example of the axial flow fan according to the present invention will be described with reference to the drawings. FIG. 16 is a bottom view of an impeller used in another example of the axial flow fan according to the present invention. The axial flow fan of the third embodiment has the same configuration as the axial flow fan A described in the first embodiment except that the configuration of the impeller 40C is different. Therefore, in the third embodiment, detailed descriptions other than the impeller 40C will be omitted.

  As shown in FIG. 16, the impeller 40 </ b> C has a configuration in which the inner fixing portion 43 of the impeller 40 is replaced with an inner fixing portion 49. The inner fixing portion 49 includes a first protrusion 491 and a second protrusion 492. The first protrusion 491 and the second protrusion 492 protrude radially inward from the inner surface in the radial direction of the hub cylindrical portion 412. The second protrusion 492 protrudes radially inward of the first protrusion 491. Thus, when the rotor yoke 33 is press-fit into the impeller hub 41, the radial outer surface of the rotor cylindrical portion 332 contacts the radial inner surface of the second projecting portion 492.

  Then, as shown in FIG. 16, a weld 494 is formed on the inner surface in the radial direction of the first protrusion 491. In addition, the second protrusion 492 is disposed radially outward of the gate mark 45. To explain further, the second protrusion 492 is located on an imaginary line VL connecting the central axis C 1 and the gate mark 45. Further, it can be said that the shortest distance between the first protrusion 491 and the gate mark 45 in the circumferential direction is longer than the shortest distance between the second protrusion 492 and the gate mark 45 in the circumferential direction.

  By forming in this manner, the weld 494 is formed in the first projecting portion 491 in which the stress at the time of press-in does not act. In addition, the second projecting portion 492 in contact with the rotor cylindrical portion 332 is disposed in the vicinity of the gate mark 45 whose strength is high. Therefore, deformation when press-fitting the rotor yoke 33 into the impeller hub 41 can be suppressed. The first protrusion 491 includes a first region 4901 opposed to the radial outer surface of the rotor cylindrical portion 332 via a gap. Further, the second protrusion 492 includes a second region 4902 in radial contact with the radial outer surface of the rotor cylindrical portion 332.

  The other features are the same as in the first embodiment.

  As mentioned above, although embodiment of this invention was described, within the range of the meaning of this invention, embodiment can be variously deformed.

  An example of the axial flow fan A according to the present invention includes a rotor portion 30 having a shaft 31 disposed along a central axis C1 extending vertically, and a stator portion 20 disposed radially opposite the rotor portion 30. And an impeller hub 41 fixed to the rotor portion 30 and rotatable integrally with the rotor portion 30. The impeller hub 41 is an injection molded product, and includes a hub top plate 411 extending in a direction perpendicular to the axial direction, a cylindrical hub cylinder 412 extending axially downward from the outer edge of the hub top 411, and a hub cylinder. The outer surface 412 has a plurality of vanes 42 arranged in the circumferential direction, and an inner fixing portion 43 disposed radially inward of the hub cylindrical portion 412. The rotor portion 30 includes a cylindrical rotor cylindrical portion 332 extending in the axial direction, and the inner fixing portion 43 has a weld 434 formed on the inner surface in the radial direction, and faces the outer surface of the rotor cylindrical portion 332 with a gap in the radial direction. And a second region 4302 in contact with at least a part of the outer surface of the rotor cylindrical portion 332.

  According to this configuration, it is possible to suppress the press-fit strength and the deformation of the inner fixing portion 43 due to the stress acting after the press-fit.

  In the above configuration, the inner fixing portion 43 includes a plurality of second regions 4302, and the plurality of second regions 4302 are arranged at equal intervals in the circumferential direction.

  According to this configuration, it is possible to uniformly disperse the stress of the press fit by evenly distributing the press-fit portions in the circumferential direction.

  In the above configuration, the inner fixing portion 43 may have a tubular shape extending in the axial direction. By configuring in this manner, the rigidity of the impeller hub 41 is increased, and it is possible to stably rotate.

  In the above configuration, the hub top plate portion 412 has gate marks 45 formed on one of the upper and lower surfaces, and the inner fixing portion 43 has a first wall portion 431 disposed radially outside the gate marks 45. , And the second wall 432 circumferentially adjacent to each other, and the first wall 431 has a second region 4302. Thereby, by providing the plurality of wall portions 431, stress due to press-fitting can be dispersed.

  In the above configuration, the hub top plate portion 411 has gate marks 45 formed on one of the upper and lower surfaces, and the inner fixing portion 49 is a first protrusion projecting radially inward from the inner surface of the hub cylindrical portion 412. 491 and a second projecting portion 492 projecting radially inward of the first projecting portion 491 from the inner surface of the hub cylindrical portion 412, and the shortest in the circumferential direction of the first projecting portion 491 and the gate mark 45 The distance is longer than the shortest distance in the circumferential direction between the second protrusion 492 and the gate mark 45, and the second protrusion 492 and the outer surface of the rotor cylindrical portion 332 are in radial contact with each other. With this configuration, it is possible to suppress the press-fit strength and the deformation, breakage, and the like of the inner fixed portion 43 due to the stress acting after the press-fit. Furthermore, the structure is simpler than the double cylinder structure or the structure in which the plurality of wall portions 430 are arranged in the circumferential direction, and the manufacturing cost can be reduced.

  In an example of the axial flow fan A according to the present invention, a rotor portion 30 having a shaft 31 disposed along a vertically extending central axis, and a stator portion 20 disposed radially opposite to the rotor portion 30; And an impeller hub fixed to the rotor portion and rotatable integrally with the rotor portion. The impeller hub 41 is an injection molded product, and includes a hub top plate 411 extending in a direction perpendicular to the axial direction, a cylindrical hub cylinder 412 extending axially downward from the outer edge of the hub top 411, and a hub cylinder. The outer surface 412 has a plurality of vanes 42 arranged in the circumferential direction, and an inner fixing portion 43 disposed radially inward of the hub cylindrical portion 412. The hub top plate portion 411 has a plurality of gate marks 45 arranged in the circumferential direction on one of the upper and lower surfaces, and at least a part of the outer surface of the rotor cylindrical portion 412 is adjacent to the gate mark 45 in the circumferential direction Contact is made with the inner surface of the inner fixed portion located in the region between the center of the gate mark 45 and the center of the gate mark 45 and the gate mark 45 adjacent on the other side in the circumferential direction. By doing this, by making the place where weld is difficult to be formed into the press-fit area, it is possible to firmly fix the rotor cylindrical portion 332 and the inner fixing portion 43.

  In the above configuration, the plurality of gate marks 45 are arranged at equal intervals in the circumferential direction. By configuring in this way, the stress at the time of press-fitting can be dispersed evenly (almost evenly).

  In the above configuration, at least a part of the contact region between the inner surface of the inner fixing portion 43 and the outer surface of the rotor cylindrical portion 412 is on the imaginary line VL outside the gate mark 45 in the radial direction and connecting the central axis C1 to the gate mark 45 Located in Thus, by making the place where welds are most unlikely to occur to be the press-fit region, the inner fixing portion 43 and the rotor cylindrical portion 412 can be firmly fixed and deformation of the inner fixing portion 43 can be suppressed.

  In the above configuration, the inner fixing portion may have a tubular shape extending in the axial direction. By configuring in this manner, the rigidity of the impeller hub 41 is increased, and it is possible to stably rotate.

  In the above configuration, the inner fixing portion 43 has a first wall portion 431 having a region overlapping the gate mark 45 in the radial direction, and a second wall portion 432 adjacent to the first wall portion 431 in the circumferential direction. The cylindrical portion 332 is in contact with the inner surface of the first wall portion 431. With this configuration, it is possible to disperse press-in stress.

  In the above configuration, the inner fixing portion 49 protrudes radially inward from the first projecting portion 491 from the inner surface of the hub cylindrical portion 412 and the first projecting portion 491 which protrudes radially inward from the inner surface of the hub cylindrical portion 412. And a second protrusion 492. The shortest distance between the first protrusion 491 and the gate mark 45 in the circumferential direction is longer than the shortest distance between the second protrusion 492 and the gate mark 45 in the circumferential direction, and the outer surface of the rotor cylindrical portion 332 is the second protrusion Contact with 492 in the radial direction. The structure is simpler than the double cylinder structure or the structure in which a plurality of wall portions are arranged in the circumferential direction, and the manufacturing cost can be reduced.

  The axial flow fan of the present invention can be used for a blower or the like used for cooling or the like of an electric device.

  A to B: axial flow fan, 10: housing, 11: air channel, 12: base, 120: base through hole, 121: cylinder holding portion, 13: Stationary blade, 14: bearing holding cylinder portion, 141: first bearing, 142: second bearing, 15: flange portion, 151: mounting hole, 16: intake port, 17 ..... Exhaust port, 20 ... Stator part, 21 ... Stator core, 211 ... Core back part, 212 ... Tees part, 22 ... Insulator, 23 ... Coil, 30 ... Rotor part, 31 ... shaft, 32 ... connection part, 321 ... connection hole, 322 ... yoke fixing part, 323 ... connection cylindrical part 323, 33 ... rotor yoke, 331 ... Rotor top plate portion 332 ・ ・ ・ Rotor tube portion, 333 ... central through hole, 3 4 Positioning hole 34 Rotor magnet magnet 40 Impeller 41 Impeller hub 411 Hub top plate portion 412 Hub cylindrical portion 413 1st Bosses 414 axial through holes 415 second bosses 42 blades 4201 innermost circumferential portion 4202 outermost circumferential portion 4203 first intermediate circumferential portion 4204 second intermediate circumferential portion 421 inner circumferential development wing 422 outer circumferential development wing 423 first central circumferential development wing 424 second center Circumferentially deployed wing 425 first part 43 inner fixing part 430 wall part 4301 first region 4302 second region 431 first Wall part, 432 ... second wall part, 433 ... thick part, 434 ... weld, 44 ... contact Part 45, gate mark 46, concave part 47, wall part 471, first wall part 472 second wall part, 473 rib (thick part) 48 through hole 49 inside fixed portion 4901 first region 4902 second region 491 first projecting portion 492 second projecting portion 494 · · · Weld

Claims (11)

A rotor portion having a shaft disposed along a central axis extending up and down;
A stator portion disposed radially opposite the rotor portion;
An impeller hub fixed to the rotor portion and rotatable integrally with the rotor portion;
Equipped with
The impeller hub is an injection molded product,
A hub top portion extending in a direction orthogonal to the axial direction;
A cylindrical hub cylinder extending axially downward from the outer edge of the hub top plate;
A plurality of vanes circumferentially arranged on the outer surface of the hub cylindrical portion;
An inner fixing portion disposed radially inward of the hub cylindrical portion;
Have
The rotor portion includes a cylindrical rotor cylindrical portion extending in the axial direction,
The inner fixing portion is
A weld is formed on the inner surface in the radial direction, and a first region radially opposed to the outer surface of the rotor cylindrical portion with a gap therebetween,
A second region in contact with at least a portion of the outer surface of the rotor cylinder;
Axial fan with. The inner fixing portion includes a plurality of the second regions,
The axial flow fan according to claim 1, wherein the plurality of second regions are arranged at equal intervals in a circumferential direction.   The axial flow fan according to claim 1, wherein the inner fixing portion has a tubular shape extending in an axial direction. The hub top plate portion has a gate mark formed on one of upper and lower surfaces,
The inner fixing portion is a first wall portion disposed radially outward of the gate mark;
And a second wall portion circumferentially adjacent to the first wall portion,
The axial flow fan according to claim 1, wherein the first wall portion includes the second region. The hub top plate portion has a gate mark formed on one of upper and lower surfaces,
The inner fixing portion is
A first protrusion projecting radially inward from an inner surface of the hub tubular portion;
And a second protrusion projecting radially inward of the first protrusion from the inner surface of the hub tubular portion,
The shortest distance in the circumferential direction between the first protrusion and the gate mark is longer than the shortest distance in the circumferential direction between the second protrusion and the gate mark.
The axial flow fan according to claim 1, wherein the second protrusion and an outer surface of the rotor cylindrical portion are in radial contact with each other. A rotor portion having a shaft disposed along a central axis extending up and down;
A stator portion disposed radially opposite the rotor portion;
An impeller hub fixed to the rotor portion and rotatable integrally with the rotor portion;
Equipped with
The impeller hub is an injection molded product,
A hub top portion extending in a direction orthogonal to the axial direction;
A cylindrical hub cylinder extending axially downward from the outer edge of the hub top plate;
A plurality of vanes circumferentially arranged on the outer surface of the hub cylindrical portion;
An inner fixing portion disposed radially inward of the hub cylindrical portion;
Have
The hub top plate portion has a plurality of gate marks arranged in the circumferential direction on one of the upper and lower surfaces,
At least a part of the outer surface of the rotor cylindrical portion is a central portion of the gate mark and the gate mark adjacent to one circumferential side, and a central portion of the gate mark and the gate mark adjacent to the other circumferential side An axial fan in contact with the inner surface of said inner fixed part located in the area between;   The axial flow fan according to claim 6, wherein the plurality of gate marks are arranged at equal intervals in a circumferential direction.   At least a part of the contact region between the inner surface of the inner fixing portion and the outer surface of the rotor cylindrical portion is located radially outside of the gate mark and on an imaginary line connecting the central axis and the gate mark. Or the axial flow fan of Claim 7.   The axial flow fan according to claim 6 or 7, wherein the inner fixed portion is in the form of a cylinder extending in the axial direction. The inner fixing portion is
A first wall portion having a region radially overlapping the gate mark;
And a second wall portion circumferentially adjacent to the first wall portion,
The axial flow fan according to any one of claims 6 to 8, wherein the rotor cylindrical portion contacts an inner surface of the first wall portion. The inner fixing portion is
A first protrusion projecting radially inward from an inner surface of the hub cylindrical portion;
A second protrusion projecting radially inward of the first protrusion from an inner surface of the hub cylindrical portion;
Have
The shortest distance in the circumferential direction between the first protrusion and the gate mark is longer than the shortest distance in the circumferential direction between the second protrusion and the gate mark.
The axial flow fan according to any one of claims 6 to 8, wherein an outer surface of the rotor cylindrical portion radially contacts the second projecting portion.

Images