Axial flow fan

Abstract

To provide an axial flow fan with little variation in wind in a radial direction.SOLUTION: An axial flow fan include: a rotatable blade 4 that rotates around a rotation axis X extending in a blowing direction W; and a casing 2 that has an outer frame portion 10 that forms a columnar air duct space 11 storing the rotatable blade 4, a cylindrical base portion 20 located on the rotation axis X, and a fixed blade 30 provided between an inner peripheral surface 14 of the outer frame portion 10 and an outer peripheral surface of the base portion 20 and on the downstream side in the blowing direction W with respect to the rotatable blade 4. If assuming an optional cross-section of the fixed blade 30 in the blowing direction W as a first cross-section and assuming a cross-section of the fixed blade 30 in a rotating direction F of the rotatable blade 4 than the first cross-section as a second cross-section, concerning a curvature projecting out to the upstream side in the blowing direction W of an air receiving surface 31 located on the upstream side in the blowing direction W of the fixed blade 30, the curvature of the second cross-section is larger than that of the first cross-section.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an axial fan. [Background technology]

[0002] Patent Document 1 discloses a heat dissipation fan (axial flow fan) in which fixed blades (stationary blades) are attached at an inclination angle with respect to a horizontal line perpendicular to the fan axis. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4145906 Summary of the Invention [Problem to be solved by the invention]

[0004] According to the heat dissipation fan in Patent Document 1, since there is an inclination angle between the upper end of the fixed blade and the horizontal line, the operating range near the hub can be increased to distribute air uniformly over the entire fixed blade, and it is said that the accumulation of airflow at the upper end of the fixed blade can be prevented, thereby eliminating noise caused by vortexes.

[0005] However, the heat dissipation fan of Patent Document 1 describes how the upper ends of the fixed blades are inclined to achieve uniform air distribution, but does not describe how other configurations can be used to achieve uniform air distribution. Therefore, there is room for improvement in terms of eliminating variations in air flow and making it uniform.

[0006] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide an axial flow fan with less variation in airflow in the radial direction. [Means for solving the problem]

[0007] An axial flow fan according to one aspect of the present invention includes: An axial flow fan that blows air in a blowing direction, A rotor blade that rotates around a rotation axis extending along the air blowing direction; a casing including an outer frame portion that defines a cylindrical air tunnel space in which the rotor blades are housed, a cylindrical base portion that is located on the rotation axis, and fixed blades that are provided between an inner circumferential surface of the outer frame portion and an outer circumferential surface of the base portion and downstream of the rotor blades in the air blowing direction; Equipped with A cross section of any fixed blade along the air blowing direction is defined as a first cross section, When a cross section of the fixed blade in the rotation direction of the rotor blade than the first cross section is defined as a second cross section, The curvature of the second cross section of the wind receiving surface located on the upstream side in the air blowing direction of the fixed blade protruding toward the upstream side is greater than the curvature of the first cross section. Effect of the Invention

[0008] According to the present invention, it is possible to provide an axial flow fan with less variation in airflow in the radial direction. [Brief description of the drawings]

[0009] [Figure 1] 1 is a perspective view of an axial flow fan according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a plan view showing a casing of the axial flow fan. [Diagram 3] 3 is a cross-sectional view taken along line X0-V1 in FIG. 2. [Figure 4] 3 is a cross-sectional view taken along line X0-V2 in FIG. 2. [Diagram 5] 3 is a cross-sectional view taken along line X0-V3 in FIG. 2. [Figure 6] 13A and 13B are views showing an enlarged diameter portion of the outer frame portion and the base portion. [Figure 7] FIG. 2 is a diagram showing a configuration of a fixed blade. [Figure 8] FIG. 13 is a diagram showing the flow of wind around the air outlet. [Figure 9] FIG. 13 is a diagram showing the airflow in the middle part of the air outlet. [Figure 10]FIG. 13 is a diagram showing the flow of air in the center of the air outlet. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. For the sake of convenience, the description of the components having the same reference numbers as those already described in the description of the embodiment will be omitted. Also, for the sake of convenience, the dimensions of each component shown in the drawings may differ from the actual dimensions of each component.

[0011] FIG. 1 is a perspective view showing an example of an axial flow fan according to an embodiment of the present invention. 1, the axial flow fan 1 is a fan that blows air in a blowing direction W indicated by an arrow. The axial flow fan 1 includes a casing 2 and a rotor blade 4 disposed within the casing 2.

[0012] The casing 2 has an outer frame portion 10 , a base portion 20 , and a fixed blade 30 . The outer frame 10 forms a cylindrical wind tunnel space 11 that communicates with a wind (air) suction port 12 and a wind outlet 13. The rotor blades 4 are housed in the wind tunnel space 11. Wind sucked in from the suction port 12 as the rotor blades 4 rotates is sent along the wind tunnel space 11 in a wind blowing direction W, and is sent out from the wind outlet 13 to the outside.

[0013] The base portion 20 is disposed in the radial center of the wind tunnel space 11 formed by the outer frame portion 10, along the rotation axis X of the rotor blades 4. The rotation axis X extends along the air blowing direction W. The base portion 20 is formed in a cylindrical shape, and has a cylindrical portion 21 provided on the suction port 12 side, which is upstream of the air blowing direction W, and a tapered portion 22 provided on the outlet port 13 side, which is downstream of the air blowing direction W.

[0014] The fixed blades 30 are stator blades for connecting the base portion 20 to the outer frame portion 10. The fixed blades 30 connect the base portion 20 to the outer frame portion 10, thereby fixing the base portion 20 to the radial center of the air tunnel space 11. The fixed blades 30 are provided between the inner peripheral surface of the outer frame portion 10 and the outer peripheral surface of the base portion 20. The outer radial end of the fixed blades 30 is connected to the inner peripheral surface of the outer frame portion 10. The inner radial end of the fixed blades 30 is connected to the outer peripheral surface of the base portion 20. The fixed blades 30 are provided downstream of the rotor blades 4 in the air blowing direction W.

[0015] The fixed blades 30 are stator blades formed in a thin plate shape. A plurality of fixed blades 30 (seven in the example shown in the figure) are provided radially. Here, the upstream surface of the fixed blades 30 in the air blowing direction W, i.e., the surface located on the suction port 12 side, is defined as the "wind receiving surface" 31. The downstream surface of the fixed blades 30 in the air blowing direction W, i.e., the surface located on the outlet 13 side, is defined as the "wind delivery surface" 32.

[0016] A motor 23 that rotates and drives the rotor blades 4 is fixed inside the base portion 20. The motor 23 is composed of a stator (not shown) around which a winding is wound, and a rotor (not shown) having a permanent magnet. By fixing the stator to the base portion 20, the motor 23 is fixed to the outer frame portion 10 via the base portion 20 and the fixed blades 30.

[0017] The rotor blades 4 are attached to the outer peripheral surface of a rotor blade case 41 formed in a cup shape. The rotor blade case 41 to which the rotor blades 4 are attached is provided in the wind tunnel space 11, upstream of the base portion 20 and the fixed blades 30 in the air blowing direction W. The rotor blade case 41 is fixed to the rotating shaft 24 of the motor 23. A plurality of permanent magnets constituting the rotor of the motor 23 are fixed to the inner peripheral surface of the rotor blade case 41. The rotor blades 4 rotate around the rotation axis X in conjunction with the rotation of the rotating shaft 24, and send air in the air blowing direction W.

[0018] Fig. 2 is a plan view of the casing 2 seen from the downstream side of the airflow direction W, i.e., from the air outlet 13 side of the air tunnel space 11. Fig. 3 is a cross-sectional view of the casing 2 along the airflow direction W at line X0-V1 in Fig. 2. Similarly, Fig. 4 is a cross-sectional view at line X0-V2 in Fig. 2. Similarly, Fig. 5 is a cross-sectional view at line X0-V3 in Fig. 2. Lines X0-V1, X0-V2, and X0-V3 are each cutting lines that pass through the center point of the base portion 20 and extend in the radial direction.

[0019] In the example shown in the figure, line X0-V1 is a cutting line that passes through the downstream end 34 in the air blowing direction W of the radially outer end 33 of the fixed blade 30 that is connected to the inner circumferential surface 14 of the outer frame portion 10. Line X0-V2 is a cutting line that passes through a position rotated a predetermined angle θ1 from line X0-V1 in the rotation direction F of the rotor blade 4. Line X0-V3 is a cutting line that passes through a position further rotated a predetermined angle θ2 from line X0-V2 in the rotation direction F.

[0020] In the fixed blade 30 of the axial fan 1, for example, a cross section along the airflow direction W at an arbitrary position on the fixed blade 30 is defined as a "first cross section," and a cross section at an arbitrary position on the side of the rotation direction F of the rotor blade 4 from the first cross section is defined as a "second cross section." In this case, the wind receiving surface 31 of the fixed blade 30 is configured such that the curvature of the second cross section protruding upstream in the airflow direction W is greater than the curvature of the first cross section.

[0021] For example, when comparing the curvatures of the wind receiving surface 31 protruding toward the upstream side in the airflow direction W for the cross sections of lines X0-V1, X0-V2, and X0-V3 in FIG. 2, the following magnitude relationships are obtained.

[0022] The cross section taken along line X0-V2 is a cross section passing through a position rotated by angle θ1 in the rotation direction F of the rotor blades 4 from the cross section taken along line X0-V1 which passes through the downstream end 34 of the outer end 33 of the fixed blade 30. Therefore, the curvature of the wind receiving surface 31 protruding toward the upstream side of the air blowing direction W in the cross section taken along line X0-V2 is greater than the curvature of the wind receiving surface 31 protruding toward the upstream side of the air blowing direction W in the cross section taken along line X0-V1.

[0023] Further, the cross section taken along line X0-V3 is a cross section passing through a position rotated by angle θ2 in the rotation direction F of the rotor blades 4 from the cross section taken along line X0-V2. Therefore, the curvature of the wind receiving surface 31 protruding toward the upstream side of the air blowing direction W on the cross section taken along line X0-V3 is greater than the curvature of the wind receiving surface 31 protruding toward the upstream side of the air blowing direction W on the cross section taken along line X0-V2.

[0024] 3, for example, in a cross-sectional view taken along line X0-V1, the wind receiving surface 31 of the fixed blade 30 is formed in a concave shape recessed toward the downstream side (air blowing direction side) of the air blowing direction W. In other words, the curvature of the wind receiving surface 31 protruding toward the upstream side of the air blowing direction W is a negative curvature.

[0025] 4, for example, in the cross-sectional view taken along line X0-V2, the wind receiving surface 31 of the fixed blade 30 is formed in a convex shape that bulges gently toward the upstream side (the opposite direction to the wind blowing direction) of the airflow direction W. In other words, the curvature of the wind receiving surface 31 protruding toward the upstream side of the airflow direction W is a small, positive curvature that is gentle.

[0026] Next, for example, as shown in Fig. 5, in the cross section taken along line X0-V3, the wind receiving surface 31 of the fixed blade 30 is formed in a convex shape that bulges toward the upstream side of the airflow direction W (the opposite direction to the airflow direction). The bulge toward the upstream side is larger than the bulge of the wind receiving surface 31 in the cross section taken along line X0-V2 (see Fig. 4). In other words, the curvature of the wind receiving surface 31 protruding toward the upstream side of the airflow direction W is a large positive curvature that is slightly sharper than the curvature of the wind receiving surface 31 in the cross section taken along line X0-V2. In this way, the curvature of the wind receiving surface 31 protruding toward the upstream side of the airflow direction W is larger for the wind receiving surface 31 closer to the rotation direction F of the rotor blade 4.

[0027] Furthermore, for example, the portion of the wind receiving surface 31 of the fixed blade 30 that is located on the most upstream side in the rotation direction F of the rotor blade 4, i.e., the portion that is located at the end opposite to the rotation direction F of the rotor blade 4, is formed in a concave shape that is recessed downstream in the air blowing direction W. Furthermore, for example, the portion of the wind receiving surface 31 of the fixed blade 30 that is located at the most downstream side in the rotation direction F of the rotor blade 4, i.e., the portion that is located at the end in the same direction as the rotation direction F of the rotor blade 4, is formed in a convex shape that bulges toward the upstream side of the air blowing direction W.

[0028] 6 is a cross-sectional view of the casing 2 along the airflow direction W at the line X0-V4 in FIG. 2, showing the enlarged diameter portion provided in the outer frame portion 10 and the base portion 20. As shown in FIG. As shown in Fig. 6, an outer frame rear expanded diameter portion 15 for increasing the diameter of the air tunnel space 11 is provided on the inner circumferential surface 14 of the outer frame portion 10 at the rear end of the outer frame, which is the end on the downstream side in the air blowing direction W. The outer frame rear expanded diameter portion 15 is formed so as to incline radially outward toward the downstream side in the air blowing direction W, i.e., toward the outlet 13 of the air tunnel space 11, in order to increase the diameter of the air tunnel space 11 and widen the outlet 13. The inclination of the outer frame rear expanded diameter portion 15 may be, for example, a planar inclination or a circular arc inclination.

[0029] Furthermore, an outer frame inner expanded diameter portion 16 that increases the diameter of the air tunnel space 11 is provided on the inner peripheral surface 14 of the outer frame portion 10 upstream of the outer frame rear expanded diameter portion 15 in the air blowing direction W. The outer frame inner expanded diameter portion 16 is formed to be inclined radially outward in order to increase the diameter of the air tunnel space 11 toward the downstream side of the air blowing direction W, i.e., toward the outer frame rear expanded diameter portion 15. The outer frame inner expanded diameter portion 16 is connected at its downstream end in the air blowing direction W to the upstream end in the air blowing direction W of the outer frame rear expanded diameter portion 15 so as to be an expanded diameter portion continuous with the outer frame rear expanded diameter portion 15. The inclination of the outer frame inner expanded diameter portion 16 may be, for example, a planar inclination or a circular arc inclination.

[0030] In addition, the outer peripheral surface of the base portion 20 is provided with a base enlarged diameter portion 25 for increasing the diameter of the air tunnel space 11 at the base rear end, which is the end on the downstream side in the air blowing direction W. The base enlarged diameter portion 25 is formed by an inclined surface in the tapered portion 22 of the base portion 20. The base enlarged diameter portion 25 is formed so as to be inclined radially inward as it approaches the downstream side in the air blowing direction W, i.e., as it approaches the outlet 13 of the air tunnel space 11, in order to increase the diameter of the air tunnel space 11 and widen the outlet 13. The inclination of the base enlarged diameter portion 25 may be, for example, a planar inclination or a circular arc inclination. The length L2 of the base enlarged diameter portion 25 in the air blowing direction W is set to be approximately the same length as the length L1 of the outer frame rear enlarged diameter portion 15 provided on the inner peripheral surface 14 of the outer frame portion 10 in the air blowing direction W.

[0031] FIG. 7 is a cross-sectional view of the casing 2 taken along the airflow direction W at the line X0-V4 in FIG. As shown in FIG. 7, the fixed blades 30 have their outer ends in the radial direction connected to the outer frame inner expanded diameter portion 16 and the outer frame rear expanded diameter portion 15 of the outer frame portion 10. The fixed blades 30 have their inner ends in the radial direction connected to the outer peripheral surface of the cylindrical portion 21 of the base portion 20. The shape of the wind receiving surface 31, which changes the curvature protruding upstream in the air blowing direction W, is formed so that the outer shape in the radial direction is continuous with the expanding inclination of the outer frame inner expanded diameter portion 16 and the outer frame rear expanded diameter portion 15 of the outer frame portion 10. Similarly, the inner shape in the radial direction of the wind receiving surface 31 is formed so as to be continuous with the expanding inclination of the base expanded diameter portion 25 of the base portion 20.

[0032] The inner end of the fixed blade 30 is not connected to the outer peripheral surface of the tapered portion 22 of the base portion 20. That is, the inner end of the fixed blade 30 is not connected to the base enlarged diameter portion 25 of the base portion 20. The inner end of the fixed blade 30 has a downstream edge in the airflow direction W extending radially outward from the connection point with the cylindrical portion 21, then inclines toward the downstream side of the airflow direction W and toward the radially outward side, and then extends radially outward again to connect to the outer frame rear enlarged diameter portion 15 of the outer frame portion 10. Therefore, the fixed blade 30 is not connected to the base enlarged diameter portion 25 of the base portion 20, but is provided so as to hang around the base enlarged diameter portion 25 while being separated from the base enlarged diameter portion 25. The fixed blade 30 has a notch 35 at its rear end, which is downstream in the airflow direction W at the joint with the base portion 20, that enters the upstream side of the airflow direction W and separates the fixed blade 30 from the base enlarged diameter portion 25.

[0033] The fixed blade 30 is attached so that the blade rear end 36, which is the downstream end in the air blowing direction W, is located upstream (forward) in the air blowing direction W of the outer frame rear end 17, which is the downstream end of the outer frame portion 10 in the air blowing direction W. In other words, the blade rear end 36 of the fixed blade 30 is provided in a state in which it is recessed further into the air tunnel space 11 than the delivery line 18 connecting the edge of the delivery port 13 of the air tunnel space 11. If the distance of the blade rear end 36 that has recessed into the air tunnel space 11 from the delivery line 18 is set as the recess distance L3, the recess distance L3 is set to be shorter than the length L1 of the outer frame rear expanded diameter portion 15 and the length L2 of the base expanded diameter portion 25 described above.

[0034] As described above, the axial fan 1 of this embodiment includes the casing 2 having the rotor blades 4 that rotate around the rotation axis X that extends along the airflow direction W, the outer frame 10 that defines the cylindrical air tunnel space 11 in which the rotor blades 4 are housed, the cylindrical base 20 located on the rotation axis X, and the fixed blades 30 that are provided between the inner circumferential surface 14 of the outer frame 10 and the outer circumferential surface of the base 20 and on the downstream side of the rotor blades 4 in the airflow direction W. If an arbitrary cross section of the fixed blades 30 along the airflow direction W is defined as a first cross section and a cross section of the fixed blades 30 in the rotation direction F of the rotor blades 4 relative to the first cross section is defined as a second cross section, the curvature of the wind receiving surface 31 located upstream of the fixed blades 30 in the airflow direction W protruding upstream in the airflow direction W is greater in the second cross section than in the first cross section. According to this configuration, in a cross section of the fixed blade 30 along the airflow direction W, the curvature of the wind receiving surface 31 protruding upstream in the airflow direction W is formed to be greater as the wind receiving surface 31 in the cross section of the fixed blade 30 approaches the rotation direction F of the rotor blade 4. This allows the wind flowing through the vicinity of the fixed blade 30 to be smoothly sent out to the outlet 13 of the wind tunnel space 11, and radial variation in the wind sent out from the outlet 13 to the outside can be suppressed.

[0035] In addition, in the axial flow fan 1, a portion of the wind receiving surface 31 located at the most upstream position in the rotation direction F is recessed with respect to the upstream of the air blowing direction W, and a portion of the wind receiving surface 31 located at the most downstream position in the rotation direction F is bulged with respect to the upstream of the air blowing direction W. By changing the shape of the wind receiving surface 31 to such an uneven shape, it is possible to suppress radial variation in the air blown out from the air outlet 13 to the outside.

[0036] According to the axial flow fan 1, the outer frame rear end portion, which is the end portion on the downstream side of the airflow direction W on the inner circumferential surface 14 of the outer frame portion 10, is provided with an outer frame rear expansion portion 15 that increases the diameter of the air tunnel space 11 toward the downstream side of the airflow direction W, and the base rear end portion, which is the end portion on the downstream side of the airflow direction W on the outer circumferential surface of the base portion 20, is provided with a base expansion portion 25 that increases the diameter of the air tunnel space 11 toward the downstream side of the airflow direction W. Therefore, the outer frame rear expansion portion 15 can diffuse the air flowing from the vicinity of the outer side in the radial direction of the air tunnel space 11 to the outside over a wide range without being drawn in or separated. Furthermore, the base expansion portion 25 can diffuse the air flowing from the vicinity of the inner side in the radial direction of the air tunnel space 11 to the outside over a wide range without being drawn in or separated. This can further suppress the radial variation of the air flowing out from the air outlet 13 to the outside and make it uniform.

[0037] Furthermore, according to the axial flow fan 1, a notch 35 is provided at the joint between the fixed blade 30 and the base portion 20 at the rear end portion on the downstream side in the air blowing direction W. This allows the wind flowing from the upstream side in the air blowing direction W to be guided from the notch 35 to the expanded diameter base portion 25 of the base portion 20. This allows the wind blown out from near the inner side in the radial direction of the air tunnel space 11 to be further diffused.

[0038] In addition, in the axial flow fan 1, the rear end of the fixed blades 30 is located forward of the rear end of the casing 2 in the airflow direction W. In the case of an axial flow fan configured such that the fixed blades are arranged up to the rear end of the casing, a sudden change in pressure is applied to the air that is guided by the fixed blades and flows from inside the fan to outside the fan, which causes noise. In contrast, in the present axial flow fan 1, an area in which no fixed blades are present is provided in the rear end area of ​​the casing 2, so that the pressure change in the air that is guided by the fixed blades 30 and flows to the outside of the fan can be made gentle, thereby preventing the generation of noise. In addition, the fixed blades 30 configured in this way cooperate with the outer frame rear expanded diameter portion 15 and the base expanded diameter portion 25 connected to the fixed blades 30 to further improve the radial uniformity of the air that is blown out from the air outlet 13 to the outside.

[0039] Furthermore, according to the axial flow fan 1, an outer frame inner diameter expansion section 16 is provided on the inner circumferential surface 14 of the outer frame section 10, upstream of the outer frame rear diameter expansion section 15 in the air blowing direction W, so that the diameter of the air tunnel space 11 increases downstream in the air blowing direction W. As a result, the air flowing through the air tunnel space 11 can be guided to the outer frame rear diameter expansion section 15 via the outer frame inner diameter expansion section 16, and the air blown out from near the outer side in the radial direction of the air tunnel space 11 to the outside can be smoothly diffused.

[0040] Fig. 8 is a cross-sectional view showing the state of wind passing near the fixed blade 30 and flowing in the peripheral portion of the outlet 13. Fig. 9 is a cross-sectional view showing the state of wind passing near the fixed blade 30 and flowing in the middle portion of the outlet 13. Fig. 10 is a cross-sectional view showing the state of wind passing near the fixed blade 30 and flowing in the center portion (inner portion) of the outlet 13.

[0041] As shown by the arrows in Fig. 8, the wind passing near the fixed blades 30 and flowing to the periphery of the outlet 13 passes smoothly near the fixed blades 30 along the curvature of the wind receiving surface 31 of the fixed blades 30, and flows to the periphery of the outlet 13. The wind that has flowed to the periphery of the outlet 13 flows out along the outer frame rear expanded diameter portion 15 of the outer frame portion 10 so as to be diffused radially outward over a wide area. In addition, the wind around the outlet 13 flows more smoothly and is diffused over a wide area by the fixed blades 30 that are retracted from the outlet 13 into the wind tunnel space 11.

[0042] 9, the wind passing near the fixed blades 30 and flowing to the middle part of the outlet 13 passes smoothly near the fixed blades 30 along the curvature of the wind receiving surface 31 of the fixed blades 30 and flows to the middle part of the outlet 13. The wind that has flowed to the middle part of the outlet 13 flows out smoothly in the air blowing direction W due to the fixed blades 30 that are retracted from the outlet 13 into the wind tunnel space 11.

[0043] As shown by the arrows in Fig. 10, the wind passing near the fixed blades 30 and flowing to the center of the outlet 13 smoothly passes near the fixed blades 30 along the curvature of the wind receiving surface 31 of the fixed blades 30 and flows to the center of the outlet 13. The wind that has flowed to the center of the outlet 13 flows out along the base enlarged diameter portion 25 of the base portion 20 so as to be diffused over a wide range radially inward. The wind in the center of the outlet 13 flows more smoothly and is diffused over a wide range by the fixed blades 30 that are retracted from the outlet 13 into the wind tunnel space 11. As shown in Figs. 8 to 10, the axial fan 1 can uniformly distribute the wind discharged from the outlet 13 to the outside in the radial direction.

[0044] Although the embodiment of the present invention has been described above, it goes without saying that the technical scope of the present invention should not be interpreted as being limited by the description of the embodiment. The embodiment is merely an example, and it is understood by those skilled in the art that various modifications of the embodiment are possible within the scope of the invention described in the claims. The technical scope of the present invention should be determined based on the scope of the invention described in the claims and its equivalents. [Explanation of symbols]

[0045] 1 Axial Fan 2 Casing 4 Moving blades 10 Outer frame 11 Wind tunnel space 12 Intake port 13 Outlet 14 Inner surface 15 Outer frame rear expansion part (first expansion part) 16 Enlarged diameter section inside outer frame (third enlarged diameter section) 17 Rear end of outer frame 18 Sending Line 20 Base 21 Cylindrical part 22 Tapered section 23 Motor 24 Rotational Axis 25 Base expansion section (second expansion section) 30 Fixed Blade 31 Wind-receiving surface 32 Airflow surface 33 Outer edge 34 Downstream end 35 Cutout 36 Blade rear end 41 Blade case F Rotation direction W Airflow direction X rotation axis

Claims

1. An axial flow fan that blows air in a blowing direction, A rotor blade that rotates around a rotation axis extending along the air blowing direction; a casing including an outer frame portion that defines a cylindrical air tunnel space in which the rotor blades are housed, a cylindrical base portion that is located on the rotation axis, and fixed blades that are provided between an inner circumferential surface of the outer frame portion and an outer circumferential surface of the base portion and downstream of the rotor blades in the air blowing direction; Equipped with A cross section of any fixed blade along the air blowing direction is defined as a first cross section, When a cross section of the fixed blade in the rotation direction of the rotor blade than the first cross section is defined as a second cross section, a curvature of a second cross section of the wind receiving surface located on the upstream side in the air blowing direction of the fixed blade protruding toward the upstream side is larger than a curvature of a first cross section; Axial fan.

2. a first enlarged diameter portion is provided at a rear end portion in the air blowing direction of the inner circumferential surface of the outer frame portion, the first enlarged diameter portion increasing a diameter of the air tunnel space toward a downstream side in the air blowing direction, A second enlarged diameter portion is provided at a rear end portion in the air blowing direction of the outer circumferential surface of the base portion, which increases a diameter of the air tunnel space toward a downstream side in the air blowing direction. The axial fan according to claim 1 .

3. A notch is provided at a rear end of the fixed blade in the air blowing direction at a joint with the base portion. The axial fan according to claim 1 .

4. In the air blowing direction, a rear end of the fixed blade is located forward of a rear end of the casing. The axial fan according to claim 1 .

5. A portion of the wind receiving surface located at the most upstream side in the rotation direction is recessed toward the upstream side in the air blowing direction, A portion of the wind receiving surface located at the most downstream side in the rotation direction bulges toward the upstream side in the air blowing direction. The axial fan according to claim 1 .

6. A third enlarged diameter portion is provided on an inner peripheral surface of the outer frame portion upstream of the first enlarged diameter portion, the third enlarged diameter portion increasing a diameter of the air tunnel space downstream in the air blowing direction. The axial fan according to claim 2.

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