TW201529994A - Axial flow fan and series axial flow fan - Google Patents

Abstract

An axial floss fan includes: a casino, defining a wind tunnel; a frame haying a plurality of spokes extended from the casing to the center in the radial direction of the casing so as to be across the wind tunnel, and a frame hub connecting the plurality of spokes at the center in the radial direction of the casing; a stator supported by the frame hub, in which a winding is wounded around the stator; a rotor pivotally supported by the frame hub in a rotatable manner and having a permanent magnet; an impeller fixed to the rotor and having a plurality of rotor blades; and a step part formed in at least one surface of the frame hub.

Description

Axial fan and inline axial fan

The present disclosure relates to an axial fan and an inline axial fan.

The present application claims priority based on Japanese Patent Application No. 2013-257089, filed on Dec. 12, 2013, in the Japan Patent Office, the entire disclosure of which is incorporated herein.

The axial flow fan includes: a rotary motor as a rotary drive device; and an impeller mounted on a rotary shaft of the rotary motor and having a plurality of rotary blades; and a cylindrical casing. It forms an axial flow with the impeller.

In the axial fan, high cooling performance can be achieved by increasing the rotational speed of the impeller. However, when the rotational speed of the impeller is increased, the individual vibration generated by the axial flow fan is also increased. The reason is that the vibration generated by the rotation of the rotor is transmitted to the casing through the bearing support portion (bush) and the frame having the frame hub, so that the individual of the axial flow fan The vibration will become larger.

The reduction of individual vibrations in the axial fan motor In the art, the axial fan motor has a propeller which generates a flow of air by rotation, and a motor which drives the propeller; and a bottom of the Venturi, which is available for the motor. Fixed; and venturi. The venturi is provided in such a way as to have a gap between the outer circumference of the propeller. The venturi has an outer frame portion having a substantially quadrangular outer peripheral shape, and a bell-shaped inlet portion having a substantially cylindrical inner peripheral shape. The bottom and outer frame of the venturi are connected by the foot. At the bottom of the venturi, a plurality of openings are formed (for example, refer to Japanese Laid-Open Patent Publication No. 2006-161688).

Further, a known blowing fan of the same technique includes an impeller that rotates about a central axis, and a motor that rotates the impeller, and a motor support portion that is a support motor portion; and a housing that houses the impeller and the motor. The motor support portion has a base portion having a substantially circular plate shape, and a substantially cylindrical bearing holding portion that extends in the axial direction around the central axis. All or a part (at least the base portion) of the motor support portion is made of a resin. On the surface of the base portion, a plurality of recesses having a mesh shape that are recessed in the axial direction are formed. The flat portion other than the concave portion of the base portion does not have a portion extending from the center of the base portion in the radial direction extending in the radial direction (for example, refer to Japanese Laid-Open Patent Publication No. 2012-184748).

An axial flow fan is provided with: a casing for defining a wind tunnel portion; and a frame having a plurality of spokes and a frame hub, a plurality of spokes extending from the casing toward a radially central portion of the casing so as to traverse the wind tunnel portion, the frame hub being located at a radially central portion of the casing for coupling the plurality And a stator supported by the frame hub and wound with a coil; and a rotor rotatably supported by the frame hub and having a permanent magnet; and an impeller fixed to the foregoing The rotor has a plurality of rotating blades; and a step portion formed on at least one surface of the frame hub.

1‧‧‧Rotary axis

2‧‧‧Shell

3‧‧‧ suction port

4‧‧‧Exporting

5‧‧‧Wind Cave Department

10‧‧‧ Impeller

11‧‧‧ Hub

12‧‧ ‧ socket

13‧‧‧Rotating blades

16‧‧‧ bearing

20‧‧‧ coil

30‧‧‧ permanent magnet

41‧‧‧ rotor yoke

50‧‧‧stator stack

52‧‧‧Insulators

53‧‧‧ slotting

60, 460‧‧‧ framework

61‧‧‧ spokes

62, 462‧‧‧ frame hub

62a‧‧‧ Inner Week

62b‧‧‧The outer part

63, 463‧‧ ‧ bearing support (sleeve)

64‧‧‧Flange

64a‧‧‧ suction side flange

64b‧‧‧ spout side flange

65‧‧‧ inserted through hole

66‧‧‧Departure

70‧‧‧ circuit board

71‧‧‧Connecting terminal

75‧‧‧through holes

100‧‧‧Rotary motor

110‧‧‧Outer rotor

120‧‧‧Inside stator

200, 400‧‧‧ axial fan

201‧‧‧1st axial fan

202‧‧‧2nd axial fan

300‧‧‧Inline axial fan

Fig. 1 is a cross-sectional view showing the upper half of the axial flow fan of the embodiment.

Fig. 2 is a front elevational view showing the inside of the frame of the axial flow fan of the embodiment.

Fig. 3 is a cross-sectional view showing the upper half of the frame of the axial flow fan of the embodiment.

Fig. 4 is a perspective view showing the appearance of the in-line type axial flow fan of the embodiment.

Fig. 5 is a left side view showing the appearance of the intake side of the in-line type axial flow fan of the present embodiment.

Fig. 6 is a right side view showing the appearance of the discharge side of the in-line type axial flow fan of the present embodiment.

Figure 7 is a front elevational view of the inside of the frame of the comparative axial fan.

Fig. 8 is a cross-sectional view showing the upper half of the frame of the comparative axial fan.

Fig. 9 is a schematic view for explaining the effect of reducing the vibration of the axial flow fan of the embodiment.

In the following detailed description, numerous specific details are set forth Although this is obvious, one or more embodiments may be practiced without the specific details. In other instances, known configurations and devices are schematically shown to simplify the drawings.

According to the technique of Japanese Laid-Open Patent Publication No. 2006-161688, a plurality of openings are formed in the bottom of the venturi (frame hub). However, when a plurality of openings are formed in the frame hub, the strength of the frame hub is lowered. Therefore, it has a lot of influence on the airflow on the discharge side.

Further, according to the technique of Japanese Laid-Open Patent Publication No. 2012-184748, a plurality of concave portions which are formed in a mesh shape and which are recessed in the axial direction are formed on the surface of the base portion (frame hub). However, forming a plurality of recesses in this manner is complicated. Further, in the case where the frame hub is made of metal, it is difficult to form a mesh-like recess on the surface of the frame hub.

An object of the present disclosure is to provide an axial flow fan and an inline axial flow fan as follows. In other words, the axial flow fan and the in-line axial flow fan have a simple structure and can suppress the decrease in the strength of the frame hub and the influence on the airflow on the discharge side, even when the rotation speed of the impeller is relatively high. In the high case, the individual vibration of the axial fan and the inline axial fan can still be reduced.

An axial flow fan (the present axial flow fan) according to an embodiment of the present disclosure includes a casing, a frame, a stator, a rotor, and an impeller.

The casing is defined as a wind tunnel. The frame has a plurality of spokes and a frame hub. The spokes extend from the casing toward the radially central portion of the casing so as to traverse the wind tunnel portion. A frame hub is positioned at a radially central portion of the housing for coupling the plurality of spokes. The stator is supported by the frame hub described above. In the stator, a coil is wound. The rotor is rotatably supported by the frame hub and has a permanent magnet. The impeller is fixed to the rotor and has a plurality of rotating blades.

A step portion is formed on at least one surface of the frame hub.

In the axial fan, a step portion is formed on at least one surface of the frame hub. With this step, the vibration transmitted to the frame hub can be alleviated. As a result, it is possible to transmit, for example, vibration to the housing through the frame hub.

Therefore, the present axial flow fan has a simple structure and can suppress the strength of the frame hub and the influence on the airflow on the discharge side, even when the rotational speed of the impeller is high. Reduce vibration.

Hereinafter, the axial flow fan of this embodiment will be described with reference to the drawings.

In the axial flow fan of the present embodiment, a step portion is formed on at least one surface of the frame hub of the frame. Therefore, the vibration transmitted to the frame hub can be alleviated. As a result, it is possible to suppress, for example, the frame hub The vibration is transmitted to the casing.

[Composition of axial flow fan]

First, the configuration of the axial flow fan of the present embodiment will be described with reference to Figs. 1 to 3 . Fig. 1 is a cross-sectional view showing the upper half of the axial flow fan of the embodiment. Fig. 2 is a front elevational view showing the inside of the frame of the axial flow fan of the embodiment. Fig. 3 is a cross-sectional view showing the upper half of the frame of the axial flow fan of the embodiment.

The axial fan is an air blowing device that is inhaled from one of the axial directions of the rotating shaft by the rotation of the impeller fixed to the rotating shaft of the rotating motor, and discharges air toward the other of the axial direction.

As shown in Fig. 1, the axial flow fan 200 includes an impeller 10 fixed to the rotating shaft 1, and a cylindrical casing 2. The casing 2 surrounds the outer circumference of the impeller 10 in the radial direction.

The impeller 10 is provided at the center portion and has a substantially cup-shaped boss portion 11. The impeller 10 is attached to the outer peripheral portion of the hub portion 11 and has a plurality of rotating blades 13. The hub portion 11 is fixed to the rotating shaft 1 through a socket 12.

Inside the hub 11, a rotary motor 100 as a rotary drive of the impeller 10 is provided. The rotary motor 100 of the present embodiment is constituted by, for example, an outer rotor type brushless motor. The rotary motor 100 has an inner stator 120 and an outer rotor 110. The inner stator 120 is an armature having a coil 20. The outer rotor 110 is an outer circumference disposed on the outer circumference of the inner stator 120 and has a permanent magnet 30 unit.

A plurality of rotating blades 13 are attached around the hub portion 11 of the impeller 10 to be radiated. Each of the rotor blades 13 is provided to be inclined to the axial direction of the rotary shaft 1.

The impeller 10 generates an air flow between the rotating blade 13 and the casing 2 by the rotation of the impeller 10. The rotor blade 13 is formed into a shape and a structure in which an air flow is generated from the hub portion 11 side of the impeller 10 toward the frame hub 62 side.

The rotor 110 includes a rotor yoke 41 having a substantially cup shape, a rotating shaft 1, a permanent magnet 30, and the like. The rotating shaft 1 is pressed into the center portion of the rotor yoke 41 by the socket 12.

The rotor yoke 41 is fitted into the hub portion 11. The permanent magnet 30 is adhered and fixed to the inner peripheral surface of the rotor yoke 41 along the axial direction. The rotor yoke 41 has a function of closing the magnetic lines of force from the exciting portion (outer rotor 110) to maximize the electromagnetic induction effect of the permanent magnet 30.

As a constituent material of the rotor yoke 41, for example, an iron-based magnetic material such as an SC (carbon steel) material can be used. However, the constituent material of the rotor yoke 41 is not limited to the materials exemplified.

The rotary shaft 1 is rotatably supported by the bearing 16. The bearing 16 is fixed to the inner surface of the cylindrical bearing support portion (sleeve) 63. The bearing support portion 63 is fixed to a central portion of the frame hub 62.

The frame hub 62 has a substantially cup shape and serves as a base portion of the stator 120. The frame hub 62 is disposed on one side of the axial direction of the rotating shaft 1 side. The hub portion 11 of the impeller 10 is positioned on the opposite side (the other side in the axial direction) of the frame hub 62 in the axial direction of the rotary shaft 1.

On the other hand, the stator 120 is provided with a stator stack 50, a coil 20, and the like.

The stator stack 50 is fixed to the outer surface of the bearing support portion 63. The stator stack 50 is formed by stacking a plurality of thin metal plates in a substantially annular shape in the thickness direction. As a constituent material of the metal plate of the stator stack 50, for example, in order to coexist performance and cost, it may be a ruthenium steel plate. A plurality of metal plates in the stator stack 50 are laminated, for example, by mechanical crimping.

In the stator stack 50, an insulator 52 is protruded. Between the insulators 52, a slot 53 as a recess is defined. The slits 53 are disposed substantially equally along the circumferential direction of the stator stack 50. In the slot 53, a coil 20 wound around the stator stack 50 is housed.

The frame hub 62 supports a circuit board (printed substrate) 70. In the circuit board 70, a wiring pattern for controlling the axial flow fan 200 is formed.

The coil 20 wound around the stator stack 50 and the circuit board 70 are electrically connected through the connection terminal 71. The connection terminal 71 is formed by concentrating the connection wires of the coil 20 and connecting them to the circuit board 70.

A through hole 75 through which the connection terminal 71 is inserted is provided in the circuit board 70. The protruding portion of the connection terminal 71 inserted through the through hole 75 is soldered to the circuit board 70.

The casing 2 defines a wind tunnel portion 5 for guiding the airflow, and at both ends, the air intake port 3 and the discharge port 4 are defined. The casing 2 is integrally formed with the frame 60 having the flange portion 64 (see Fig. 2). The flange portion 64 of the present embodiment is formed in a rectangular shape. An insertion hole 65 for attaching a mounting screw (not shown) is provided at four corners of the flange portion 64.

As shown in FIGS. 1 to 3, the frame 60 has a plurality of spokes 61 and a frame hub 62.

The plurality of spokes 61 extend from the casing 2 toward the central portion in the radial direction of the casing 2 so as to traverse the wind tunnel portion 5. Each of the spokes 61 is formed to have a wing shape in substantially the same direction in order to have a rectifying function of the discharge airflow.

A plurality of spokes 61 are fastened to the central portion of the casing 2 in the radial direction and are coupled by a frame hub 62. The frame hub 62 is formed in a ring shape. The inner peripheral portion 62a and the outer peripheral portion 62b of the frame hub 62 are in a raised state. In the inner peripheral portion 62a of the frame hub 62, a bearing support portion (sleeve) 63 is fitted and fixed.

A step portion 66 is formed on at least one surface of the frame hub 62. In the present embodiment, two step portions 66 are formed in the inner bottom portion of the frame hub 62. The two step portions 66 are formed in a concentric shape.

In the present embodiment, two step portions 66 are formed on the inner bottom surface of the frame hub 62. The number of the step portions 66 can be determined according to the diameter of the frame hub 62, and is not limited to two. Moreover, it is not limited to the inner bottom of the frame hub 62, but may be on the surface of the frame hub 62, or both. The surface (i.e., the surface and the inner bottom) forms a step portion 66.

[Structure of Inline Axial Fan]

Next, the configuration of the in-line type axial flow fan of the present embodiment will be described with reference to Figs. 4 to 6 . Fig. 4 is a perspective view showing the appearance of the in-line type axial flow fan of the embodiment. Fig. 5 is a left side view showing the appearance of the intake side of the in-line type axial flow fan of the present embodiment. Fig. 6 is a right side view showing the appearance of the discharge side of the in-line type axial flow fan of the present embodiment.

As shown in FIGS. 4 to 6 , in the in-line type axial flow fan 300 of the present embodiment, at least the first axial fan 201 and the second shaft are connected in series in the axial direction of the rotary shaft 1 of the rotary motor 100. Flow fan 202. The first axial fan 201 is disposed on the intake side, and the second axial fan 202 is disposed on the discharge side. Further, in the present embodiment, the two axial flow fans are connected in series. It is not limited to this, and three or more axial fans may be connected in series.

In the present embodiment, the length of the first axial fan 201 in the axial direction is set to be larger than the length of the second axial fan 202 in the axial direction. The frame 60 is disposed at the discharge port of the first axial fan 201 disposed on the intake side (see FIGS. 1 and 2).

In the in-line axial fan 300 of the present embodiment, the rotation of the first axial fan 201 is sequentially arranged in the cylindrical casings 2 and 2 connected in series along the airflow direction. Blade 13 (refer to Fig. 5), frame 60 as fixed blade, and second axial fan Rotating blade 13 of 202 (refer to Fig. 6). Further, a frame may be disposed on the discharge side of the second axial fan 202.

The first axial fan 201 and the second axial fan 202 have substantially the same structure except for the first axial fan 201 and the frame 60 as a fixed blade.

The structure of the first axial fan 201 may be the same as that of the above-described axial fan 200. The configuration of the second axial fan 202 may be the same as the above-described axial fan 200 except for the point of the frame 60. Therefore, the detailed internal structure of the second axial fan 202 will be omitted.

In the second axial fan 202, the axial position of the rotor 110 and the stator 120 to which the circuit board 70 is attached is reversed from the first axial fan 201 (see FIG. 1). In the first axial flow fan 201 and the second axial flow fan 202, even if the positions of the internal structure are reversed, the axial flow fans 201 and 202 connected in series can set the direction or the rotation direction of the rotary blades 13 to form the same direction. Airflow (see Figures 5 and 6).

[The role of axial fans and in-line axial fans]

Next, the operation of the axial flow fan 200 and the in-line type axial flow fan 300 of the present embodiment will be described with reference to Figs. 1 to 3, 4, and 7 to 9.

As shown in FIG. 4, the first axial fan 201 and the second axial fan 202 of the present embodiment are connected in series, for example, in an in-line type as an in-line type axial fan (in-line type fan motor) 300.

The in-line type axial flow fan 300 is, for example, a casing attached to an electronic device. In the attachment of the in-line axial fan 300 to the casing, the mounting screw is screwed through the intake side flange portion 64a of the casing 2 or the insertion hole 65 of the discharge side flange portion 64b. For example, when the in-line type axial flow fan 300 is used as a cooling fan for a server, the intake side flange portion 64a is attached to the fan attachment portion on the inner surface of the frame of the server.

The impeller 10 of the first axial fan 201 and the impeller 10 of the second axial fan 202 rotate, for example, in opposite directions. By rotating the impeller 10 of the first axial fan 201 and the second axial fan 202, air can be taken in from the intake port 3 of the first axial fan 201.

The air taken in from the intake port 3 of the first axial fan 201 passes through the rotating blades 13 of the first axial fan, the frame 60 as the fixed blade, and the rotating blades 13 of the second axial fan 202 in this order. The discharge is discharged from the discharge port 4 of the second axial fan 202.

As shown in FIGS. 1 to 3, the frame 60 of the axial flow fan 200 (201) of the present embodiment has a plurality of spokes 61. The plurality of spokes 61 extend from the casing 2 toward the central portion in the radial direction of the casing 2 so as to traverse the wind tunnel portion 5. A plurality of spokes 61 are fastened to the central portion of the casing 2 in the radial direction and are coupled by a frame hub 62.

On the other hand, the rotating shaft 1 of the rotor 110 passes through the bearing support portion (sleeve) 63 and the bearing 16 fixed to the frame hub 62, and the shaft is rotatably supported. The impeller 10 is fixed to the rotor 110 and has a plurality of rotating blades 13.

Therefore, when it is desired to increase the rotational speed of the impeller 10 to achieve higher cooling performance, the individual vibration generated by the axial flow fan 200 also becomes large. That is, the vibration generated by the rotation of the rotor 110 is transmitted to the casing 2 through the bearing support portion (sleeve) 63 and the frame 60 having the frame hub 62. Therefore, the individual vibration of the axial flow fan 200 becomes large.

Then, in the axial flow fan 200 (201) of the present embodiment, the step portion 66 is formed on at least one surface of the frame hub 62. In the present embodiment, the step portion 66 is formed at the inner bottom portion of the frame hub 62. According to the axial flow fan 200 (201) of the present embodiment, the vibration transmitted to the frame hub 62 can be alleviated by the step portion 66 formed at the inner bottom portion of the frame hub 62. Therefore, the vibration transmitted to the frame hub 62 will be difficult to pass to the casing 2.

Further, in the inner bottom portion of the frame hub 62 of the present embodiment, two step portions 66 are formed. Since the aforementioned two step portions 66 are formed in a concentric shape, the vibration can be alleviated without bias.

Further, the step portion 66 is formed on one side of the frame hub 62 instead of the opening portion. Therefore, the step portion 66 does not affect the airflow on the discharge side. Further, the number of the step portions 66 can be determined in accordance with the diameter of the frame hub 62.

<Comparative form>

Next, referring to Fig. 7 to Fig. 9, comparison is made with an axial flow fan having a frame of a conventional structure as a comparative form, and the effect of the axial flow fan 200 of the present embodiment is reviewed. Figure 7 is a comparison of the axes of the form Inside front view of the frame of the flow fan. Fig. 8 is a cross-sectional view showing the upper half of the frame of the comparative axial fan. Fig. 9 is a schematic view for explaining the effect of reducing the vibration of the axial flow fan of the embodiment.

As shown in FIGS. 7 and 8, in the axial fan 400 of the comparative embodiment, the inner bottom surface of the frame hub 462 of the frame 460 is formed to be smooth. Further, the surface of the frame hub 462 is also formed to be smooth.

<Vibration measurement result>

The individual vibration is measured in both the axial flow fan 200 of the present embodiment and the axial flow fan 400 of the comparative embodiment. The measurement results of the above-described form are shown in Fig. 9.

As shown in Fig. 9, in the axial flow fan (Example) 200 of the present embodiment, when compared with the axial fan (comparative example) 400 of the comparative embodiment, an effect of reducing the vibration by about 50% can be obtained.

This can be considered as follows. In the comparative axial fan (comparative example) 400, the both sides of the frame hub 462 are smooth. Therefore, the vibration generated by the rotation of the rotor is easily transmitted to the casing 2 through the bearing support portion (sleeve) 463 and the frame 460 having the frame hub 462. As a result, the individual vibration of the axial fan 400 becomes large.

As described above, in the axial fan 200 and the inline axial fan 300 of the present embodiment, the step portion 66 is formed on at least one surface of the frame hub 62. By the step portion 66, the vibration transmitted from the rotor 110 to the frame hub via the bearing support portion (sleeve) 63 can be alleviated. As a result, the vibration is not easily transmitted to the casing 2.

Therefore, the axial flow fan 200 and the in-line axial flow fan 300 of the present embodiment have a simple structure and can suppress the decrease in the strength of the frame hub 62 and the influence on the airflow on the discharge side, even in the impeller. In the case where the rotation speed of 10 is high, the individual vibration of the axial flow fan 200 and the inline type axial flow fan 300 can be reduced.

The preferred embodiments of the present disclosure have been described above. The above-described embodiments are illustrative of the technical description of the disclosure, and do not limit the scope of the disclosure. The technology disclosed in the present invention can be implemented in various aspects different from the above-described embodiments without departing from the gist of the invention.

Further, the present disclosure is also an improvement in the frame structure of an axial flow fan and an in-line axial flow fan in which a rotary motor is incorporated in an impeller having a plurality of rotating blades. The frame 60 of the axial flow fan 200 and the in-line axial flow fan 300 of the present embodiment has a simple structure and can suppress the decrease in the strength of the frame hub 62 and the influence on the airflow on the discharge side, even when In the case where the rotational speed of the impeller 10 is high, the individual vibration of the axial flow fan 200 and the inline axial flow fan 300 can be reduced.

The step portion 66 may also be expressed as a groove portion or an annular groove portion.

Another object of the present invention is to provide an axial flow fan and an in-line axial flow fan having a frame, which has a simple structure, does not reduce the strength of the frame hub, and does not affect the air flow on the discharge side, even if it is a high rotation. Speed can still reduce individual vibration.

Further, the embodiment of the present disclosure may be the following axial flow fan. The axial flow fan has a housing for defining a wind tunnel portion, and a frame having a plurality of spokes and a frame hub, the plurality of spoke systems being in the past The housing extends toward the radially central portion of the housing in a manner transverse to the wind tunnel portion, the frame hub is located at the central portion for connecting the plurality of spokes; and the stator is configured by the frame hub And a rotor wound around the frame hub and having a permanent magnet; and an impeller fixed to the rotor and having a plurality of rotating blades in the frame hub At least one of the faces is formed with a step portion.

In the axial flow fan, the step portion may be formed in a concentric shape on the inner bottom surface of the frame hub.

Further, in the in-line type axial flow fan of the present disclosure, the axial flow fan may be connected in series to a plurality of axial directions of the rotating shaft of the rotor.

The foregoing detailed description has presented the purpose of illustration and illustration. Various modifications and changes can be made based on the above teachings. The specific form disclosed is not intended to be exhaustive or to limit the invention. Although the subject matter of the present invention has been described in language specific to structural features and/or methodological acts, it is understood that the subject matter defined in the appended claims is not limited to the specific features or acts described. Instead, the specific features and acts described above are intended to be illustrative of the scope of the application.

1‧‧‧Rotary axis

2‧‧‧Shell

3‧‧‧ suction port

4‧‧‧Exporting

5‧‧‧Wind Cave Department

10‧‧‧ Impeller

11‧‧‧ Hub

12‧‧ ‧ socket

13‧‧‧Rotating blades

16‧‧‧ bearing

20‧‧‧ coil

30‧‧‧ permanent magnet

41‧‧‧ rotor yoke

50‧‧‧stator stack

52‧‧‧Insulators

53‧‧‧ slotting

60‧‧‧Frame

61‧‧‧ spokes

62‧‧‧Frame hub

63‧‧‧ bearing support

66‧‧‧Departure

70‧‧‧ circuit board

71‧‧‧Connecting terminal

75‧‧‧through holes

100‧‧‧Rotary motor

110‧‧‧Outer rotor

120‧‧‧Inside stator

200‧‧‧axial fan

Claims (3)

An axial flow fan, comprising: a casing for defining a wind tunnel portion; and a frame having a plurality of spokes and a frame hub, wherein the plurality of spokes are arranged to cross the wind tunnel portion Extending from the housing toward a radially central portion of the housing, the frame hub being located at a radially central portion of the housing for coupling the plurality of spokes; and a stator that is coupled to the frame hub Supporting and winding a coil; and a rotor rotatably supported by the frame hub and having a permanent magnet; and an impeller fixed to the rotor and having a plurality of rotating blades; and a step portion It is formed on at least one surface of the frame hub. The axial flow fan according to claim 1, wherein the plurality of the step portions are formed concentrically on the inner bottom surface of the frame hub. An in-line type axial flow fan comprising: the axial flow fan according to claim 1 or 2, wherein the axial flow fans are in an axial direction connected in series to a rotation axis of the rotor.