JP2013113128A - Axial flow fan - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an axial flow fan with a large air flow and static pressure.SOLUTION: The axial flow fan 100 comprises an impeller 10 mounted to a rotary shaft 21 of a rotary driving device 20, and a venturi casing 30 surrounding the outer circumference in the radial direction of the impeller 10 and having an intake port 41 and a discharge port 42 facing each other in the axial direction of the rotary shaft 21. The inner surface of the venturi casing 30 has an intake side inclined portion 31 with the intake port 41 enlarged outward in the radial direction of the impeller 10, a linear portion 32 provided continuously from the intake side inclined portion 31 for forming an axial flow of a fluid together with the impeller 10, a discharge side inclined portion 34 with the discharge port 42 enlarged outward in the radial direction of the impeller 10, and a curved portion 33 connecting the linear portion 32 and the discharge side inclined portion 34.

Description

  The present invention relates to an axial fan having an improved inner surface shape of a venturi casing that surrounds an outer periphery in the radial direction of an impeller.

  The axial fan includes a cylindrical venturi casing that forms an axial flow with the impeller on the outer periphery in the radial direction of the impeller attached to the rotation shaft of the rotary drive device. Since the axial fan has a simple structure, it is widely used, for example, as a cooling fan for a personal computer or a ventilation fan.

  This axial fan generally has a blowing characteristic that the air volume is large and the static pressure is small. In order to improve the blowing characteristics of such an axial fan, various devices have been applied to the structure of the impeller and the structure of the venturi casing.

  For example, in Patent Document 1, the cross section of an orifice (venturi casing) is configured by a part or all of an arc portion, a straight portion, and a discharge side arc portion on the suction side, and the arc radius of the suction side arc portion is set to the discharge side arc portion. An air blower formed larger than the radius of the arc is disclosed.

  Patent Document 2 discloses an axial fan in which a taper surface concentric with the rotation center of a fan is formed in a casing (venturi casing), and an inclined portion along the intake side taper surface is formed in a rotary blade. Yes.

JP-A-5-133398 JP 2000-179490 A

  By the way, the air blower of patent document 1 implement | achieves low noise, obtaining large air volume by forming the circular arc radius of a suction side circular arc part larger than the circular arc radius of a discharge side circular arc part. However, the discharge port of the venturi casing is enlarged only at the discharge-side arc portion. Therefore, since the discharge flow passes through the inner surface of the venturi casing with a sharp change in direction, the maximum static pressure tends to be smaller than when the discharge port is expanded linearly.

  On the other hand, the axial fan of Patent Document 2 has the inclined portion of the rotating blades along the intake-side tapered surface of the venturi casing to smooth the air flow during intake and suppress the occurrence of turbulence. However, since there is a restriction on the expansion of the intake port by the intake side taper surface of the venturi casing due to the relationship with the inclined portion of the rotary blade, there is a limit to the increase in the air volume.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide an axial fan having a large air volume and a high static pressure.

  An axial fan for achieving the above object includes an impeller and a venturi casing. An impeller is attached to the rotating shaft of a rotation drive device. The venturi casing has an intake port and a discharge port that surround the outer periphery in the radial direction of the impeller and face the axial direction of the rotating shaft.

  The inner surface of the venturi casing includes an intake side inclined portion that expands the intake port radially outward of the impeller, a linear portion that continues from the intake inclined portion and forms an axial flow of fluid with the impeller, and a discharge port. A discharge-side inclined portion that expands radially outward of the impeller, and a curved portion that connects the linear portion and the discharge-side inclined portion.

  The discharge-side inclined portion expands the discharge port linearly from the curved portion outward in the radial direction of the impeller.

  According to the axial fan according to the present invention, since the intake port is inclined and expanded outward in the radial direction of the impeller by the intake side inclined portion, the fluid around the intake port can be sucked, The air volume can be increased.

  In addition, the inner surface of the venturi casing has a curved portion connecting a straight portion that forms an axial flow with the impeller and a discharge-side inclined portion. The discharge-side inclined portion expands the discharge port linearly from the curved portion outward in the radial direction of the impeller.

  Therefore, since the direction of the discharge flow is changed in a curved portion at a curved portion and then smoothly guided along the straight discharge-side inclined portion, a large static pressure can be obtained while suppressing the occurrence of turbulence. it can.

It is sectional drawing which shows the axial fan which concerns on this embodiment. It is sectional drawing which shows the principal part of the axial fan of this embodiment. 6 is a cross-sectional view showing a main part of an axial fan according to Comparative Example 1. FIG. It is sectional drawing which shows the principal part of the axial-flow fan of the comparative example 2. It is a figure explaining the characteristic of the axial fan of an Example by the relationship with the characteristic of the comparative examples 1 and 2. FIG.

  Hereinafter, an axial fan according to the present embodiment will be described with reference to the drawings.

  First, the axial fan of this embodiment will be described with reference to FIG. FIG. 1 is a sectional view showing an axial fan according to the present embodiment. FIG. 2 is a cross-sectional view showing a main part of the axial fan of the present embodiment.

  The axial fan sucks air from one axial direction of the rotary shaft 21 and discharges fluid to the other axial direction by the rotation of the impeller 10 attached to the rotary shaft 21 of the rotary drive device 20 described later. It is. The axial fan 100 according to the present invention can provide an axial fan having a large air volume and maximum static pressure by improving the inner surface shape of the casing 30 surrounding the outer periphery in the radial direction of the impeller 10.

  As shown in FIG. 1, the axial fan 100 according to the present embodiment includes an impeller 10 attached to a rotary shaft 21 of a rotary drive device 20 and a venturi casing (hereinafter, referred to as a radial outer periphery of the impeller 10). 30). Furthermore, the axial fan 100 of this embodiment includes a frame 40. The frame 40 supports the base portion 22 of the rotational drive device 20 and supports the casing 30 integrally.

  The impeller 10 has a cup-shaped hub portion 11 at the center, and a plurality of blades 12 are integrally attached radially around the hub portion 11. Each blade 12 is provided to be inclined with respect to the axial direction of the rotation shaft 21.

  Inside the hub portion 11, a motor is provided as the rotational drive device 20 for the impeller 10. The motor 20 includes a substantially cup-shaped rotor yoke 23, a rotary shaft 21 press-fitted into the center of the rotor yoke 23, a stator core 26 around which a coil 25 is wound.

  The rotor yoke 23 is fitted into the hub portion 11. A magnet 24 is fixed to the inner peripheral surface of the rotor yoke 23.

  The rotating shaft 21 is rotatably supported by the bearing 27. The bearing 27 is fixed to the inner surface of the cylindrical support portion 28. The support portion 27 is integrally fixed to a circular opening hole 22 a formed at the center of the base portion 22.

  The stator core 26 is press-fitted and fixed to the outer surface of the support portion 27. The stator core 26 and the magnet 24 of the rotor yoke 23 are opposed to each other with a gap.

  The frame 40 is formed of, for example, synthetic resin, and the motor 20 is installed on the base portion 22 on the intake side, and is formed integrally with the cylindrical casing 30 and houses the impeller 10 therein. The base 22 and the casing 30 are connected by radial spokes 43.

  Further, flange portions 51 and 52 for fixing the frame 40 to an electronic device or the like are provided on the periphery of the intake side and the discharge side of the casing 30. The flange portions 51 and 52 extend from the intake side and the discharge side of the casing 30 outward in the radial direction of the impeller 10, respectively. These flange portions 51 and 52 are square-shaped attachment members that are continuous with the outer peripheral wall of the casing 30. Screw holes (not shown) for screwing attachment screws are formed at the four corners of the flanges 51 and 52.

  Accordingly, the axial fan 100 is attached to the casing or the like by screwing a mounting screw (not shown) to the intake side flange portion 51 or the discharge side flange portion 52 via the casing of the electronic device. For example, when the axial fan 100 of the present embodiment is used as a cooling fan for a personal computer (PC), the intake side flange portion 51 is attached to the fan attachment portion on the inner surface of the casing of the PC. Moreover, when using the axial fan 100 of this embodiment as a ventilation fan, the discharge side flange part 52 is attached to the opening peripheral part of a building wall.

  Next, with reference to FIG. 2, the inner surface shape of the casing 30 in this embodiment is demonstrated. The axial fan 100 according to the present invention is characterized by the inner shape of the casing 30.

  As shown in FIG. 2, the inner surface of the casing 30 is composed of an intake side inclined portion 31, a straight portion 32, a curved portion 33, and a discharge side inclined portion 34 from the intake side to the discharge side. It is continuous.

  The intake side inclined portion 31 is a portion that expands the intake port 41 outward in the radial direction of the impeller 10. The intake side inclined portion 31 of the present embodiment is formed by a curved line such as an arc, and the intake port 41 is curvedly expanded outward in the radial direction of the impeller 10. However, the intake side inclined portion 31 may expand the intake port 41 linearly outward in the radial direction of the impeller 10.

  In this manner, the intake port 41 is inclined and enlarged by the intake side inclined portion 31, whereby the fluid around the intake port 41 can be sucked and the airflow of the axial fan 100 can be increased. Here, the air volume is the volume of air that is sucked and discharged by the axial fan 100 per unit time. The larger the pressure ratio, the smaller the air volume on the discharge side due to compression, so the air volume on the intake side is usually used.

  The straight portion 32 is a portion that continues from the intake side inclined portion 31 and is connected to the intake side inclined portion 31 and the curved portion 33 by a straight line, and forms an axial flow of fluid together with the impeller 10. The straight portion 32 faces the tip side of the blade 12 of the impeller 10 with a gap, and extends to the discharge side substantially parallel to the tip side of the blade 12.

  The curved portion 33 is a portion that continues from the straight portion 32 and connects the straight portion 32 and a discharge-side inclined portion 34 described later with a curved line. The curved portion 33 of the present embodiment is formed by, for example, an arc having a radius R of 5 mm, but is not limited to the numerical value of the radius in the present embodiment.

  The boundary between the curved portion 33 and the straight portion 32 is located on the static pressure boundary line PL between the intake side static pressure and the discharge side static pressure of the impeller 10. Therefore, the boundary between the curved portion 33 and the straight portion 32 is the boundary between the intake side and the discharge side of the inner surface of the casing 30.

  Here, the pressure is generated by the centrifugal force of the impeller 10, and the fluid reaches farther as the maximum static pressure increases. The intake-side static pressure gradually decreases from 0 Pa to the PL line as a negative static pressure and becomes the minimum. On the other hand, the discharge side static pressure becomes the maximum static pressure with the PL line as a boundary, and gradually decreases to 0 Pa again.

  The discharge-side inclined portion 34 is a portion that continues from the curved portion 33 and expands the discharge port 42 outward in the radial direction of the impeller 10. The discharge side inclined portion 34 expands the discharge port 42 linearly from the curved portion 33 outward in the radial direction of the impeller 10. Therefore, the discharge flow that has passed through the impeller 10 is smoothly guided along the straight discharge-side inclined portion 34 after the curved portion 33 changes its direction in a curved direction outward in the radial direction of the impeller 10. The The discharge side inclined portion 34 of the present embodiment has an inclination angle of, for example, 44 degrees with respect to the vertical line, but is not limited to the numerical value of the inclination angle in the present embodiment.

  Further, in the present embodiment, the inner diameter of the discharge port 42 expanded by the discharge side inclined portion 34 is set larger than the inner diameter of the intake port 41 expanded by the intake side inclined portion 31. Since the inner diameter of the discharge port 42 is set to be larger than the inner diameter of the intake port 41 in this way, the discharge flow changes from an axial flow to a diagonal flow, and a pressure increasing action due to the centrifugal force of the impeller is added, thereby providing sufficient pressure characteristics. Will be obtained.

  As described above, the axial fan 100 according to the present embodiment increases the air volume by inhaling the fluid around the intake port 41 by inclining and expanding the intake port 41 at the intake side inclined portion 31. Can do.

  Further, the inner surface of the casing 30 connects the discharge-side inclined portion 34 and the linear portion 32 that forms an axial flow with the impeller 10 by a curved portion 33. The discharge-side inclined portion 34 expands the discharge port 42 linearly from the curved portion 33 outward in the radial direction of the impeller 10.

  Therefore, since the direction of the discharge flow is curvilinearly changed outward in the radial direction of the impeller 10 by the curved portion 33, and further smoothly guided along the straight discharge-side inclined portion 34, the turbulent flow A large static pressure can be obtained while suppressing the occurrence.

  Therefore, the axial flow fan 100 of this embodiment expands the discharge port 42 by combining the curved portion 33 and the linear discharge side inclined portion 34, thereby suppressing the generation of turbulent flow, the air volume and the maximum static pressure. The large air blowing characteristic can be obtained.

  The preferred embodiments of the present invention have been described above, but these are examples for explaining the present invention, and the scope of the present invention is not intended to be limited to these embodiments. The present invention can be implemented in various modes different from the above-described embodiments without departing from the gist thereof.

Hereinafter, although an example and a comparative example are given and an axial fan concerning the present invention is explained still in detail, the present invention is not limited to this example.
〔Example〕
With reference to FIG. 1 and FIG. 1 again, an embodiment of the axial fan according to the present invention will be described. In this example, the axial fan 100 shown in FIGS. 1 and 2 was produced. In the axial fan 100 of the embodiment, as described above, the discharge-side inner surface of the casing 30 is formed by the curved portion 33 and the discharge-side inclined portion 34. The radius R of the curved portion 33 is set to 5 mm. Further, the discharge side inclined portion 34 is set to 44 degrees from the vertical line.

The blowing characteristics of the axial fan 100 of the example are measured with respect to the flow velocity, the maximum air volume, the maximum static pressure, the noise, and the power consumption, and verified by comparison with Comparative Examples 1 and 2 described later.
[Comparative Example 1]
With reference to FIG. 3, the axial fan 200 of the comparative example 1 is demonstrated. FIG. 3 is a cross-sectional view showing a main part of the axial fan of the first comparative example. Note that the same configuration as the embodiment will be described using the same reference numerals.

  As shown in FIG. 3, the axial fan 200 of the comparative example 1 is different from the embodiment in the shape of the inner surface on the discharge side of the casing 60. The inner surface of the casing 60 in the comparative example 1 is composed of an intake side inclined portion 31, a straight portion 32, and a discharge side inclined portion 64 from the intake side to the discharge side, and these portions are successively arranged.

  The intake side inclined portion 31 and the straight portion 32 are formed in the same manner as in the embodiment. The discharge-side inclined portion 64 linearly enlarges the discharge port 42 and is set at an inclination angle of 53 degrees from the vertical line. That is, the axial fan 200 of the comparative example 1 is formed by only the discharge side inclined portion 64 where the discharge side of the inner surface of the casing 60 is linear.

The blowing characteristics of the axial flow fan 200 of Comparative Example 1 are measured with respect to the flow velocity, the maximum air volume, the maximum static pressure, the noise, and the power consumption, and verified in comparison with the Example and the Comparative Example 2.
[Comparative Example 2]
With reference to FIG. 4, the axial-flow fan 300 of the comparative example 2 is demonstrated. FIG. 4 is a cross-sectional view showing a main part of the axial fan of Comparative Example 2. Note that the same configuration as the embodiment will be described using the same reference numerals.

  As shown in FIG. 4, the axial fan 300 of Comparative Example 2 is different from the Examples and Comparative Example 1 in the shape of the inner surface of the casing 70 on the discharge side. The inner surface of the casing 70 in the comparative example 2 is composed of the intake side inclined portion 31, the straight portion 32, and the discharge side arc portion 74 from the intake side to the discharge side, and these portions are successively arranged.

  The intake side inclined portion 31 and the straight portion 32 are formed in the same manner as in the example and the comparative example 1. Further, the discharge-side arc portion 74 enlarges the discharge port 42 in a curve, and is set to an arc having a radius R of 7.72 mm. That is, in the axial fan 300 of the comparative example 2, the discharge side of the inner surface of the casing 60 is formed by only the discharge-side arc portion 64.

The blowing characteristics of the axial fan 300 of Comparative Example 2 are measured with respect to the flow velocity, the maximum air volume, the maximum static pressure, the noise, and the power consumption, and verified by comparing with the Example and the Comparative Example 1.
[Verification of ventilation characteristics of Examples and Comparative Examples 1 and 2]
FIG. 5 is a diagram illustrating the characteristics of the axial fan according to the embodiment in relation to the characteristics of Comparative Examples 1 and 2.

As shown in FIG. 5, the flow rates of Example and Comparative Examples 1 and 2 are 5850 [min ⁻¹ ], and all show the same value.

The maximum air volume of Example and Comparative Example 2 is 1.74 [m ³ / min], which shows the same value. However, the maximum air volume of Comparative Example 1 is 1.70 [m ³ / min], which is inferior to the maximum air volumes of Example and Comparative Example 2. Therefore, regarding the maximum air volume, it is considered that a larger air volume can be obtained by enlarging the discharge port 42 in a curved line than by linearly expanding it.

  The maximum static pressures of the example and the comparative example 1 are 112.9 [Pa] and 112.8 [Pa], respectively, indicating substantially the same values. However, the maximum static pressure in Comparative Example 2 is 109.0 [Pa], which is inferior to the maximum static pressure in Examples and Comparative Example 1. Regarding the maximum static pressure, it is considered that a larger static pressure can be obtained when the discharge port 42 is linearly expanded than when it is expanded in a curved line.

  The noise of Example and Comparative Examples 1 and 2 was 44.2 [dB], 44.3 [dB], and 44.2 [dB], respectively, indicating substantially the same value.

  The power consumption of Example and Comparative Examples 1 and 2 is 3.35 [W], 3.30 [W], and 3.35 [W], respectively, indicating substantially the same value.

  That is, according to the embodiment, the axial fan 100 having a large air volume and static pressure can be obtained by combining the curved portion 33 and the linear discharge-side inclined portion 34 to expand the discharge port 42.

  The axial fan according to the present invention can be widely applied as a cooling fan for an electronic device such as a personal computer or a power supply device, or a ventilation fan.

10 impeller,
20 rotary drive,
21 rotation axis,
30 Venturi casing,
31 Inlet side inclined part,
32 straight section,
33 Curved part,
34 Discharge side inclination,
41 Inlet,
42 Discharge port,
100 Axial fan PL Static pressure boundary line.

Claims (4)

An impeller attached to the rotary shaft of the rotary drive device;
A venturi casing that surrounds the outer periphery in the radial direction of the impeller and has an intake port and a discharge port facing the axial direction of the rotating shaft,
The inner surface of the venturi casing is
An intake-side inclined portion that expands the intake port radially outward of the impeller;
A linear portion that is continuous from the intake inclined portion and forms an axial flow of fluid with the impeller; and
A discharge-side inclined portion that expands the discharge port radially outward of the impeller; and
A curved portion connecting the straight portion and the discharge-side inclined portion;
An axial fan characterized by comprising:   The axial flow fan according to claim 1, wherein a boundary between the straight portion and the curved portion is located on a static pressure boundary line between an intake side static pressure and a discharge side static pressure of the impeller.   3. The axial flow according to claim 1, wherein an inner diameter of the discharge port enlarged by the discharge-side inclined portion is larger than an inner diameter of the intake port enlarged by the intake-side inclined portion. fan.   The axial flow fan according to any one of claims 1 to 3, wherein the discharge-side inclined portion expands the discharge port linearly from the curved portion outward in the radial direction of the impeller.