Axial flow fan

Abstract

Provided is an axial flow fan capable of achieving an improvement in P-Q characteristics.　This axial flow fan (100) comprises: a casing (10) in which a flow path (130) communicating an intake port (11) and an exhaust port (12) is formed; and an impeller (20) that is disposed inside the casing (10), comprises a hub part (21) and a plurality of moving blades (30), and can rotate around an axis, wherein the plurality of moving blades each have a front edge part (33) and a rear edge part (34), the rear edge part (34) includes a first portion (37) disposed on the inner peripheral side and a second portion (38) disposed on the outer peripheral side, the second portion (38) includes an inclined surface inclined at a different angle than the first portion (37), and the inclined surface of the second portion (38) is inclined so that the blade thickness of the second portion (38) is smaller than the blade thickness of the first portion (37).

Description

Axial flow fan

[0001] The present disclosure relates to an axial fan.

[0002] For example, an axial flow fan has a hub that is rotated by an external rotational force and a plurality of blades that extend radially around the hub (see, for example, Patent Document 1).The axial flow fan of Patent Document 1 has a recess formed on the negative pressure side of the blade, which reduces the thickness of the blade.

[0003] JP 2010-242665 A

[0004] Axial flow fans are required to have improved airflow-static pressure characteristics, also known as PQ characteristics.

[0005] An object of the present disclosure is to provide an axial flow fan that can improve air volume-static pressure characteristics.

[0006] An axial flow fan according to one aspect of the present disclosure comprises: a casing having an intake port and an exhaust port, the casing having a flow path formed therein that connects the intake port to the exhaust port; and an impeller disposed within the casing and rotatable about an axis, the impeller comprising a hub portion and a plurality of rotor blades formed on the hub portion, the plurality of rotor blades having a leading edge portion disposed on the intake port side and a trailing edge portion disposed on the exhaust port side, the trailing edge portion including a first portion disposed on the inner peripheral side and a second portion disposed on the outer peripheral side, the second portion including an inclined surface inclined at an angle different from that of the first portion, and the inclined surface of the second portion being inclined so that the blade thickness of the second portion is thinner than the blade thickness of the first portion.

[0007] The present disclosure can provide an axial flow fan that can improve air volume-static pressure characteristics.

[0008] FIG. 1 is a cross-sectional view showing an example of an axial fan according to an embodiment; FIG. 2 is a side view showing an example of an impeller of the axial fan; FIG. 3 is a perspective view showing an example of an impeller of the axial fan from the rear; FIG. 4 is a front view showing an example of an impeller of the axial fan; FIG. 5 is a rear view showing an example of an impeller of the axial fan; FIG. 6 is a cross-sectional view showing an example of a rotor blade of the impeller; FIG. 7 is a side view showing an enlarged example of a trailing edge portion of the rotor blade; FIG. 8 is a side view showing an enlarged example of an rotor blade; FIG. 9 is a front view showing an enlarged example of an impeller; FIG. 10 is a side view showing an enlarged example of a trailing edge portion of the rotor blade; FIG. 11 is a plan view showing an example of a rotor blade.

[0009] Non-limiting examples of the present invention will be described with reference to the accompanying drawings. In the accompanying drawings, identical or corresponding members or components are designated by identical or corresponding reference numerals. Further, duplicate descriptions of identical or corresponding members or components will be omitted below. Furthermore, members or components are not necessarily drawn to scale in the drawings. Therefore, those skilled in the art can arbitrarily determine specific dimensions by referring to the following non-limiting examples. Furthermore, the following examples are illustrative rather than limiting the invention. Furthermore, the features and combinations thereof described in the examples are not necessarily essential to the invention.

[0010] Axial fan according to an embodiment Fig. 1 is a cross-sectional view showing an example of an axial fan 100 according to an embodiment. In some of the drawings, the X-axis direction, Y-axis direction, and Z-axis direction, which are perpendicular to one another, are shown. The Z-axis direction is the direction in which the shaft 15 extends. The X-axis direction and the Y-axis direction are along the radial direction. The shaft 15 is an example of an axis. When simply referred to as the "axial direction," it refers to the direction in which the shaft 15 extends. When simply referred to as the "radial direction," it refers to the radial direction of the shaft 15, a direction perpendicular to the axial direction. The radial direction includes the X-axis direction and the Y-axis direction.

[0011] Furthermore, in this specification, the terms "upper" and "lower" may be used. In this case, the up-down direction refers to the direction in which the shaft 15 extends, with the side closer to the intake port 11 being "upper" and the side closer to the exhaust port 12 being "lower." Note that the actual arrangement of the axial fan 100 may or may not follow this. The shaft 15 may be arranged along the up-down direction or along the horizontal direction.

[0012] In addition, in this specification, the terms "intake port side" and "exhaust port side" may be used. The "intake port side" is the side closer to the intake port. The "exhaust port side" is the side closer to the exhaust port.

[0013] The axial fan 100 shown in FIG. 1 is a blower that can be used to cool electronic devices such as servers. The axial fan 100 is attached to the housing of the electronic device and supplies air to the inside of the housing to cool the electronic device inside the housing. The axial fan 100 is not limited to cooling electronic devices and can be used for other purposes. The axial fan 100 can blow air. The axial fan 100 may also blow gases other than air.

[0014] The axial flow fan 100 includes a casing 10, a shaft 15, an impeller 20, a base portion 50, and a motor 60. The axial flow fan 100 includes a plurality of rotor blades 30 formed on the impeller 20, and fixed blades 70 formed on the inner circumferential surface of the casing 10. The impeller 20 includes a hub portion 21, the plurality of rotor blades 30, and a cylindrical portion 40.

[0015] [Casing] The casing 10 is formed with an intake port 11 and an exhaust port 12. The intake port 11 and the exhaust port 12 face each other in the Z-axis direction.

[0016] The casing 10 may be formed to form a rectangular parallelepiped. The casing 10 may be formed to form a cube. The casing 10 may be formed to form a cylindrical shape or other shapes. The casing 10 may be formed with a flange or a bracket.

[0017] A flow path 130 is formed inside the casing 10, extending from the intake port 11 toward the exhaust port 12. In the Z-axis direction, the side closer to the intake port 11 is referred to as "upstream," and the side closer to the exhaust port 12 is referred to as "downstream." In addition, in the Z-axis direction, the side closer to the intake port 11 may be referred to as "front," and the side closer to the exhaust port 12 may be referred to as "rear."

[0018] The casing 10 accommodates an impeller 20, a base 50, a motor 60, and fixed blades 70. Inside the casing 10, the impeller 20, the motor 60, and the base 50 are arranged in this order from the side closest to the intake port 11. The base 50 is arranged in a position close to the exhaust port 12.

[0019] [Air Intake Port and Exhaust Port] The air intake port 11 and the exhaust port 12 are formed at positions facing each other in the Z-axis direction. The air intake port 11 may be the most upstream end of the flow path 130. The exhaust port 12 may be the most downstream end of the flow path 130.

[0020] [Shaft] The shaft 15 extends in the Z-axis direction. The shaft 15 is a rotation axis of the motor 60. The shaft 15 is rotatably supported by the casing 10. The shaft 15 has an end 15a and an end 15b. The ends 15a and 15b are ends of the shaft 15 in the longitudinal direction. The end 15a is located closer to the intake port 11, and the end 15b is located closer to the exhaust port 12.

[0021] [Bearings] The axial fan 100 includes a pair of bearings 16, 17 that rotatably support the shaft 15. The bearings 16, 17 are spaced apart in the Z-axis direction. The bearing 16 is located closer to the intake port 11, and the bearing 17 is located closer to the exhaust port 12. The bearings 16, 17 may be, for example, rolling bearings. The bearings 16, 17 are fixed to the casing 10 via, for example, the base portion 50.

[0022] The axial flow fan 100 may include, for example, a bearing support member 18 that holds a pair of bearings 16 and 17. The bearing support member 18 extends in the Z-axis direction. An end of the bearing support member 18 on the exhaust port 12 side is fixed to the base portion 50. The bearing support member 18 includes a cylindrical portion. The pair of bearings 16 and 17 are held inside the cylindrical portion of the bearing support member 18. The shaft 15 supported by the pair of bearings 16 and 17 is disposed inside the cylindrical portion of the bearing support member 18. An end 15a of the shaft 15 on the intake port 11 side protrudes further toward the intake port 11 in the Z-axis direction than the cylindrical portion of the bearing support member 18.

[0023] [Base Portion] The base portion 50 is disposed inside the casing 10. The base portion 50 is disposed at a position close to the exhaust port 12 in the Z-axis direction. A portion of the base portion 50 may be disposed inside the exhaust port 12.

[0024] The base portion 50 supports the motor 60, the bearing support member 18, the pair of bearings 16 and 17, the shaft 15, and the impeller 20. The base portion 50 is fixed to the casing 10, for example, via a fixed blade 70. The base portion 50 includes, for example, a boss portion 51, a hub portion 52, and a cylindrical portion 53. The boss portion 51 is disposed in the center of the casing 10 when viewed in the Z-axis direction. The boss portion 51 supports the end of the bearing support member 18 on the exhaust port 12 side. The boss portion 51 has, for example, a cylindrical shape. The boss portion 51, the hub portion 52, and the cylindrical portion 53 are, for example, integrally molded.

[0025] The hub portion 52 is, for example, disk-shaped. The thickness direction of the hub portion 52 is along the Z-axis direction. The boss portion 51 is disposed at the radial center of the hub portion 52 when viewed from the Z-axis direction. The hub portion 52 is formed in the Z-axis direction so as to cover the motor 60 when viewed from outside the exhaust port 12.

[0026] The cylindrical portion 53 is connected to the outer periphery of the hub portion 52. The cylindrical portion 53 protrudes from the hub portion 52 toward the intake port 11 in the Z-axis direction. A downstream portion of the flow path 130 is formed between the outer periphery of the cylindrical portion 53 and the inner periphery of the casing 10.

[0027] The base portion 50 is fixed to the casing 10 via the fixed blades 70. The cylindrical portion 53 is connected to the casing 10 via the fixed blades 70. The base portion 50 may be supported by the casing 10 via, for example, a rod-shaped member extending in the radial direction.

[0028] [Stator blades] The multiple stator blades 70 extend radially from the inner peripheral surface of the casing 10 toward the outer peripheral surface of the tubular portion 53 of the base portion 50. The length of the multiple stator blades 70 in the Z-axis direction may be approximately the same as the length of the tubular portion 53 of the base portion 50, for example.

[0029] The multiple fixed vanes 70 may be formed in a spiral shape having an angle with respect to the circumferential direction of the shaft 15. The fixed vanes 70 may be formed up to the rear end of the casing 10 in the Z-axis direction. The rear end of the casing 10 may be located at the position of the exhaust port 12. As described above, the fixed vanes 70 connect the base portion 50 and the casing 10 in the radial direction.

[0030] [Motor] The motor 60 is disposed inside the cylindrical portion 40 of the impeller 20. The motor 60 has a rotor 61 and a stator 62. The stator 62 is disposed radially inward of the rotor 61. The rotor 61 is disposed radially outward of the stator 62.

[0031] The rotor 61 has a magnet 63 and an iron core (rotor yoke) 64 arranged radially outward of the stator 62. The iron core 64 includes a disk portion and a cylindrical portion. The disk portion is fixed to the end portion 15a of the shaft 15 on the intake port 11 side. The cylindrical portion protrudes from the disk portion in the Z-axis direction toward the exhaust port 12 side. The magnet 63 has, for example, a cylindrical shape. The magnet 63 is fixed to the inner circumferential surface of the cylindrical portion of the iron core 64.

[0032] The stator 62 is disposed radially inside the magnet 63. The stator 62 includes, for example, an insulator 65, an iron core (stator core) 66, and a coil 67. The stator 62 is fixed to the outer peripheral surface of the bearing support member 18. The iron core 66 is, for example, ring-shaped and is fixed to the outer peripheral surface of the bearing support member 18. The coils 67 are disposed on both sides of the iron core 66 in the Z-axis direction. The insulator 65 is disposed so as to cover the coil 67 in the radial direction. The insulator 65 is disposed radially between the coil 67 and the magnet 63.

[0033] The rotor 61, the impeller 20, and the shaft 15 rotate as a unit.

[0034] [Impeller] Fig. 2 is a side view showing an example of the impeller 20 of the axial fan 100. Fig. 3 is a perspective view showing an example of the impeller 20 of the axial fan 100 from the rear. Fig. 4 is a front view showing an example of the impeller 20 of the axial fan 100. Fig. 5 is a rear view showing an example of the impeller 20 of the axial fan 100. As described above, the impeller 20 shown in Figs. 1 to 5 includes a hub portion 21 and a plurality of rotor blades 30. The hub portion 21 includes a cylindrical portion 40. As shown in Fig. 1, a flow passage 130 is formed in the radial direction between the outer peripheral surface of the impeller 20 and the inner peripheral surface of the casing 10.

[0035] [Hub portion] The hub portion 21 includes a head portion 22 and a tubular portion 40. The head portion 22 is, for example, disk-shaped. The head portion 22 is the portion of the hub portion 21 on the intake port 11 side. The outer periphery of the head portion 22 is connected to the tubular portion 40. The head portion 22 may be, for example, dome-shaped. The head portion 22 may be curved in a cross section along the Z-axis direction. The head portion 22 is arranged to cover the opening of the tubular portion 40 on the intake port 11 side.

[0036] [Cylindrical portion] The cylindrical portion 40 protrudes from the head portion 22 in the Z-axis direction toward the exhaust port 12. The cylindrical portion 40 is disposed closer to the intake port 11 than the cylindrical portion 53 of the base portion 50. The cylindrical portion 40 of the impeller 20 and the cylindrical portion 53 of the base portion 50 are aligned in the Z-axis direction. The outer peripheral surface of the cylindrical portion 40 of the impeller 20 and the outer peripheral surface of the cylindrical portion 53 of the base portion 50 are formed at the same position in the radial direction.

[0037] [Rotor Blades] The multiple rotor blades 30 protrude radially outward from the hub portion 21. The multiple rotor blades 30 are formed on the hub portion 21. Formed on the hub portion 21 includes being formed relative to the hub portion 21. The multiple rotor blades 30 protrude radially outward from the outer circumferential surface of the head portion 22 and the outer circumferential surface of the tubular portion 40. For example, five rotor blades 30 are formed. The multiple rotor blades 30 are formed so as to be continuous in the circumferential direction and the Z-axis direction of the impeller 20. The number of the multiple rotor blades 30 is not limited to five.

[0038] Fig. 6 is a cross-sectional view showing an example of the rotor blade 30 of the impeller 20. Fig. 6 shows a cross section of the rotor blade 30 along the circumferential direction of the impeller 20. The circumferential direction of the impeller 20 may be the rotation direction of the impeller 20. As shown in Fig. 6, the rotor blade 30 has a leading edge 31 and a trailing edge 32. The leading edge 31 is the upstream end, and is the end on the intake port 11 side. The trailing edge 32 is the downstream end, and is the end on the exhaust port 12 side.

[0039] The rotor blade 30 has a leading edge portion 33 and a trailing edge portion 34. The leading edge portion 33 is the portion of the rotor blade 30 on the leading edge 31 side. The trailing edge portion 34 is the portion of the rotor blade 30 on the trailing edge 32 side. The leading edge portion 33 includes the leading edge 31 and a portion downstream of the leading edge 31. The trailing edge portion 34 includes the trailing edge 32 and a portion upstream of the trailing edge 32.

[0040] The rotor blade 30 has a first surface 35 and a second surface 36. The first surface 35 and the second surface 36 face each other in the blade thickness direction of the rotor blade 30. The first surface 35 is the back surface of the rotor blade 30 and is the low-pressure side surface. The second surface 36 is the pressure side of the rotor blade 30 and is the high-pressure side surface. The first surface 35 is the surface on the intake port 11 side in the Z-axis direction, and the second surface 36 is the surface on the exhaust port 12 side.

[0041] [First and second portions of the trailing edge portion] The trailing edge portion 34 includes a first portion 37 and a second portion 38. The first portion 37 includes an inner peripheral portion of the trailing edge portion 34. The second portion 38 includes an outer peripheral portion of the trailing edge portion 34. The inner peripheral side is the cylindrical portion 40 side in the radial direction of the impeller 20. The outer peripheral side is the inner peripheral surface side of the casing 10 in the radial direction of the impeller 20.

[0042] The thickness of the second portion 38 is thinner than the thickness of the first portion 37. At the trailing edge 34 of the blade 30, the thickness of the second portion 38 on the outer periphery side is thinner than the thickness of the first portion 37 on the inner periphery side. At the trailing edge 34, the blade 30 has the second portion 38 with a thinner thickness on the outer periphery side. The thinner portion may be expressed as having a notched portion compared to the thicker portion. The thinner portion may also be expressed as a notch. The surface of the thinner portion may also be expressed as a ground surface. Even if the surface is not actually ground, it may be expressed as a ground surface. "The thickness of the second portion 38 is thinner than the thickness of the first portion 37" may mean, for example, that the second portion 38 includes a portion thinner than the first portion 37 and does not include a portion thicker than the first portion 37, as shown in FIG. 10 , when viewed in the radial direction.

[0043] 5 , the trailing edge 32 is disposed so as to be inclined with respect to the radial direction of the tubular portion 40 when viewed in the Z-axis direction. The radial direction is a direction perpendicular to the outer peripheral surface of the tubular portion 40. The outer peripheral side of the trailing edge 32 is disposed closer to the leading edge 31 in the circumferential direction of the tubular portion 40 than the inner peripheral side of the trailing edge 32.

[0044] Furthermore, among multiple circumferentially adjacent rotor blades 30, a portion of the trailing edge 34 of one rotor blade 30 overlaps a portion of the leading edge 33 of the other rotor blade 30. The trailing edge 32 of one rotor blade 30 and the leading edge 31 of the other rotor blade 30 are arranged to intersect when viewed in the Z-axis direction. In other words, when viewed in the Z-axis direction, the trailing edge 32 of the front rotor blade 30 is arranged to intersect with the leading edge 31 of the rear rotor blade 30 in the rotation direction of the tubular portion 40.

[0045] In the rotation direction of the tubular portion 40, the inner peripheral position of the trailing edge 32 of the front rotor blade 30 is located further rearward than the inner peripheral position of the leading edge 31 of the rear rotor blade 30. In the rotation direction of the tubular portion 40, the outer peripheral position of the trailing edge 32 of the front rotor blade 30 is located further forward than the outer peripheral position of the leading edge 31 of the rear rotor blade 30.

[0046] The trailing edge 32 of the second portion 38 is disposed closer to the leading edge portion 33 than the trailing edge 32 of the first portion 37 in the rotation direction of the tubular portion 40. In other words, the trailing edge 32 of the second portion 38 is disposed forward of the trailing edge 32 of the first portion 37 in the rotation direction of the tubular portion 40.

[0047] [Angle of First Surface of Second Portion] Next, the angle of the first surface 35 of the second portion 38 of the rotor blade 30 will be described with reference to Fig. 7. Fig. 7 is an enlarged side view showing an example of the trailing edge portion 34 of the rotor blade 30. Fig. 7 shows the trailing edge portion 34 of the rotor blade 30 from the radially outer side.

[0048] 7 shows straight lines L1 to L3 made up of dashed dotted lines. Line L1 is a line along a UV plane perpendicular to the Z-axis direction. The UV plane is a plane parallel to the U-axis direction and the V-axis direction. The U-axis direction is one of the radial directions, and the V-axis direction is a direction perpendicular to the Z-axis direction and the U-axis direction. The U-axis direction is a radial direction connecting two points at the same position in the Z-axis direction (axial direction of the hub portion 21), and as shown in FIG. 9, is a radial direction connecting the axis center PO of the hub portion 21 and a position P15 of the tip of the inclined surface of the second portion 38 at the outer peripheral edge 30a of the rotor blade 30.

[0049] The straight line L2 is a tangent line along the upstream (leading edge) surface 35a of the first surface 35 of the rotor blade 30. As shown in FIG. 7 , the straight line L2 is a straight line along the ZV plane, and may be a tangent line along the upstream (leading edge) surface 35a of the first surface 35 of the rotor blade 30 when viewed from the U-axis direction. The upstream surface 35a is a surface upstream of the second portion 38. The upstream surface 35a may be a surface with a normal shape (a normal profile surface) that has not been thinned (cut). Note that the straight line L2 may be a tangent line along the surface 35a in a virtual plane that passes through positions P13 and P15 in FIG. 8 (described later) and is aligned with the Z-axis.

[0050] The straight line L3 is a tangent line along the first surface 35b in the second portion 38 of the rotor blade 30. The first surface 35b is included in the second portion 38. The surface 35a is an example of a first region. The first surface 35b is an example of a second region.

[0051] The straight lines L2 and L3 intersect with the straight line L1 at different angles θ1 and θ2. The angle θ1 is the angle at which the straight lines L1 and L2 intersect. The angle θ1 is the smaller of the angles at which the straight lines L1 and L2 intersect. As described above, the straight line L2 is a tangent line along the upstream (leading edge) surface 35a of the first surface 35 of the rotor blade 30. As shown in FIG. 6 , the first surface 35 is curved. The straight line L2 is the tangent line that is tangent to the upstream surface 35a of the first surface 35 and that has the largest angle θ1 with respect to the straight line L1. The straight line L2 may be a tangent line at a position closest to the position P15 on the upstream side of the position P15. The angle θ2 is the angle at which the straight lines L1 and L3 intersect. The angle θ2 is the smaller of the angles at which the straight lines L1 and L3 intersect. The angle θ2 is larger than the angle θ1. The angle θ2 may be equal to or smaller than the angle θ1+20°. The angle difference Δθ between the angle θ2 and the angle θ1 may be, for example, a maximum of 20°.

[0052] The angle difference Δθ between the angle θ2 and the angle θ1 is the angle at which the line L2 intersects with the line L3. The angle difference Δθ may be, for example, 2 degrees or more and 20 degrees or less, or 3 degrees or more and 10 degrees or less. The angle difference Δθ is an example of the tilt angle of the second region relative to the first region.

[0053] [Range of Inclined Surface in Axial Direction] Next, the range of the inclined surface (second portion 38) in the axial direction (Z-axis direction) of the impeller 20 will be described with reference to Fig. 8. Fig. 8 is an enlarged side view showing an example of a rotor blade 30. Fig. 8 also shows the overall length L4 of the impeller 20 in the Z-axis direction. The overall length L4 of the impeller 20 in the Z-axis direction is the length from a position P11 of the tip end of the hub portion 21 of the impeller 20 to a position P12 of the rear end of the tubular portion 40.

[0054] 8 illustrates the total length L5 in the Z-axis direction of the multiple rotor blades 30. The total length L5 in the Z-axis direction of the rotor blade 30 may be the length from a position P13 of the leading edge 31 to a position P14 of the trailing edge 32 at the outer circumferential edge 30a of the rotor blade 30.

[0055] Position P13 of the leading edge 31 is located closer to the exhaust port 12 (rear, lower) in the Z-axis direction than position P11 of the tip of the impeller 20. Position P14 of the trailing edge 32 is located closer to the intake port 11 (forward, higher) in the Z-axis direction than position P12 of the rear end of the impeller 20. Overall length L5 of the rotor blade 30 in the Z-axis direction is shorter than overall length L4 of the impeller 20 in the Z-axis direction.

[0056] 8 illustrates the length L6 of the inclined surface of the second portion 38 in the Z-axis direction. The length L6 of the inclined surface of the second portion 38 in the Z-axis direction may be the length from the leading end position P15 to the trailing end position P16 of the inclined surface. Position P15 may be, for example, a position on the outer peripheral edge 30a. Position P16 is a position on the inner peripheral side of the outer peripheral edge 30a.

[0057] In the Z-axis direction, the length L6 of the inclined surface of the second portion 38 may be 5% to 35% or 10% to 25% of the total length L5 of the outer peripheral edge of the rotor blade 30.

[0058] [Range of the inclined surface relative to the entire length of the outer peripheral edge] Next, the range of the inclined surface relative to the entire length R1 of the outer peripheral edge 30a will be described with reference to Fig. 9. Fig. 9 is an enlarged front view of an example of the impeller 20. Fig. 9 is a view of the impeller 20 as viewed in the Z-axis direction from the intake port 11 side.

[0059] 9 illustrates the overall length R1 of the outer peripheral edge 30a of the rotor blade 30. The overall length R1 of the outer peripheral edge 30a of the rotor blade 30 is the length from position P13 of the leading edge 31 to position P14 of the trailing edge 32 in the circumferential direction of the impeller 20. Positions P13 and P14 are positions on the outer peripheral edge 30a.

[0060] 9 shows the length R2 of the inclined surface of the second portion 38 on the outer peripheral edge 30a. The length R2 of the inclined surface of the second portion 38 is the length from the leading end position P15 of the inclined surface to the trailing end position P14. Positions P15 and P14 are positions on the outer peripheral edge 30a.

[0061] In the rotation direction of the impeller 20, the length R2 of the inclined surface of the second portion 38 may be, for example, 5% to 35% or 5% to 25% of the total length R1 of the outer peripheral edge 30a of the rotor blade 30.

[0062] [Inclination Angle of Inclined Surface with Respect to Reference Line] Next, the inclination angle θ3 of the inclined surface of the second portion 38 with respect to the straight line L1, which is the reference line, will be described with reference to Figure 10. Figure 10 is an enlarged side view showing an example of the trailing edge portion 34 of the rotor blade 30. In Figure 10, inclination angles θ3 to θ5 are shown. Figure 10 is a view of the rotor blade 30 as viewed, for example, in the U-axis direction (radial direction). As described above, the U-axis direction is the radial direction connecting the axis center PO and position P15 (see Figure 9).

[0063] The inclination angle θ3 is the inclination angle of the inclined surface (first surface 35) of the second portion 38 with respect to the straight line L1. The inclination angle θ4 is the inclination angle of the second surface 36 of the second portion 38 with respect to the straight line L1. The inclination angle θ5 is the inclination angle of the first surface 35 of the first portion 37 with respect to the straight line L1.

[0064] The angle θ6 is the angle of the inclined surface of the second portion 38 relative to the first portion 37 of the first surface 35. The angle θ6 may be, for example, 2 degrees or more and 20 degrees or less, or 3 degrees or more and 10 degrees or less. The first portion 37 is the first portion disposed on the inner circumferential side, and the second portion 38 is the second portion disposed on the outer circumferential side.

[0065] [Length of Inclined Surface in the Direction Along the Trailing Edge] Next, with reference to Figure 11, the length of the inclined surface in the direction along the trailing edge 32 of the second portion 38 will be described. Figure 11 is a plan view showing an example of the rotor blade 30. Figure 11 illustrates lengths L11 and L12. Length L11 is the length of the trailing edge 32, and is the length from position P17 of the inner circumferential edge to position P14 of the outer circumferential edge 30a.

[0066] The length L12 is the length of the inclined surface in the direction along the trailing edge 32 of the second portion 38. The length L12 is the length from position P16 to position P14a. The length L12 may be, for example, 10% to 100%, 10% to 50%, or 20% to 40% of the length L11. The trailing edge 32 may be formed, for example, linearly or curvedly when viewed in the blade thickness direction. The position P14a is a position on the outer peripheral edge 30a and may be the position on the inclined surface of the second portion 38 closest to the trailing edge 32.

[0067] [Method of Processing Impeller 20] The impeller 20 can be processed using, for example, a molding die. The shape of the rotor blades 30 may be formed using a molding die, or may be formed by, for example, cutting or polishing. The method of processing the impeller 20 is not limited. Furthermore, the material of the impeller 20 is not limited.

[0068] [Operations and Effects of Axial Fan According to the Embodiment] The axial fan 100 according to the embodiment includes: a casing 10 having an intake port 11 and an exhaust port 12 and having a flow passage 130 formed therein that communicates from the intake port 11 to the exhaust port 12; and an impeller 20 disposed within the casing 10 and rotatable about its axis, the impeller 20 including a hub portion 21 and a plurality of rotor blades 30 formed on the hub portion 21. The rotor blades 30 each have a leading edge 33 disposed on the intake port 11 side and a trailing edge 34 disposed on the exhaust port 12 side. The trailing edge 34 includes a first portion 37 disposed on the inner circumferential side and a second portion 38 disposed on the outer circumferential side. The second portion 38 includes an inclined surface that is inclined at an angle different from that of the first portion 37. The blade thickness of the second portion 38 is thinner than the blade thickness of the first portion 37. The inclined surface of the second portion 38 is inclined so that the blade thickness of the second portion 38 is thinner than the blade thickness of the first portion 37 .

[0069] In this type of axial fan 100, an inclined surface is formed on the outer periphery of the trailing edge 34 of the rotor blade 30, and a second portion 38 is formed with a blade thickness thinner than that on the inner periphery. With this type of axial fan 100, it is possible to improve the air volume-static pressure characteristics. With the axial fan 100, it is possible to improve fan efficiency and increase the air volume. Furthermore, with the axial fan 100, the second portion 38 with a blade thickness thinner than that on the inner periphery is formed on the outer periphery, thereby improving acoustic vibration performance. Improving acoustic vibration performance means reducing vibration and noise. With the axial fan 100, it is possible to suppress vibration and noise.

[0070] In the axial flow fan 100, the trailing edge 32 of the second portion 38 is positioned closer to the leading edge 33 than the trailing edge 32 of the first portion 37 in the rotational direction (circumferential direction) of the impeller 20. With the axial flow fan 100 having this structure, it is possible to improve the air volume-static pressure characteristics as well as the acoustic vibration characteristics.

[0071] In the axial fan 100, each of the rotor blades 30 has a first surface 35 located on the intake port 11 side in the Z-axis direction and a second surface 36 located on the exhaust port 12 side in the Z-axis direction. The first surface 35 includes a first region on the leading edge 31 side and a second region on the trailing edge 32 side. The second portion 38 has a second region, which includes an inclined surface that is inclined at a different angle relative to the first region. The inclined surface of the second region is inclined so that the blade thickness is thinner than that of the first region.

[0072] The inclination angle (angle difference Δθ) of the second region relative to the first region in the radial direction may be 2 degrees or more and 20 degrees or less, or 3 degrees or more and 10 degrees or less. An axial flow fan 100 having such a structure can improve air volume-static pressure characteristics and acoustic vibration characteristics. The above-mentioned radial direction is the radial direction along the U-axis direction shown in FIG. 9 . As described above, the U-axis direction is the radial direction connecting two points that are at the same position in the axial direction (Z-axis direction) of the hub portion 21, i.e., the radial direction connecting the position PO of the axis of the hub portion 21 and the position P15 of the tip of the inclined surface of the second portion 38 at the outer peripheral edge 30 a of the rotor blade 30.

[0073] In addition, in the axial fan 100, the length L6 of the second portion 38 in the Z-axis direction may be 5% or more and 35% or less, or 10% or more and 25% or less, of the length L5 from the leading edge 31 to the trailing edge 32 at the outer peripheral edge 30a of the multiple rotor blades 30.

[0074] In addition, in the axial fan 100, in the rotation direction of the impeller 20, the length R2 of the second portion 38 at the outer peripheral edge 30a of the multiple rotor blades 30 may be 5% or more and 35% or less, or 5% or more and 25% or less, of the total length R1 of the outer peripheral edge 30a.

[0075] In the axial fan 100, the length of the second portion 38 at the trailing edge 32 of the rotor blade 30 in the direction in which the trailing edge 32 extends may be 10% to 100%, 10% to 50%, or 20% to 40% of the overall width of the rotor blades 30. In the axial fan 100, the length L12 of the second portion 38 in the direction in which the trailing edge 32 extends may be 10% to 100%, 10% to 50%, or 20% to 40% of the length L11 corresponding to the overall width of the rotor blade 30. The position of the second portion 38 closest to the trailing edge 32 may be position P14 on the trailing edge 32 or position P14a (see FIG. 11 ) shifted toward the leading edge from the trailing edge 32. The direction in which the trailing edge 32 of the rotor blade 30 extends may be the radial direction at the position where the trailing edge 32 is located.

[0076] The preferred embodiments of the present invention have been described above in detail. However, the present disclosure is not limited to the above-described embodiments. Various modifications, substitutions, etc. may be applied to the above-described embodiments without departing from the scope of the present disclosure. Furthermore, features described separately may be combined unless technical contradictions arise.

[0077] In the above embodiment, a case is described in which an inclined surface is formed on the first surface 35 on the outer periphery of the trailing edge portion 34 of the rotor blade 30, but an inclined surface (cut surface) may also be formed on the second surface 36 on the outer periphery of the trailing edge portion 34.

[0078] In the above embodiment, the trailing edge 34 and the leading edge 33 of the rotor blades 30 adjacent in the rotation direction of the impeller 20 overlap when viewed in the Z-axis direction, but the trailing edge 34 and the leading edge 33 of the rotor blades 30 adjacent in the rotation direction do not have to overlap. The trailing edge 34 and the leading edge 33 of the rotor blades 30 adjacent in the rotation direction may be spaced apart.

[0079] In the above embodiment, an example is given of the case where the trailing edge 32 and leading edge 31 of adjacent rotor blades 30 in the rotation direction of the impeller 20 intersect with each other when viewed in the Z-axis direction, but the trailing edge 32 and leading edge 31 do not have to intersect.

[0080] This international application claims priority based on Japanese Patent Application No. 2023-147821, filed on September 12, 2023, the entire contents of which are incorporated herein by reference.

[0081] 100...axial fan, 10...casing, 11...intake port, 12...exhaust port, 15...shaft, 20...impeller, 21...hub portion, 30...rotor blade, 30a...outer peripheral edge, 31...leading edge, 32...trailing edge, 33...leading edge portion, 34...trailing edge portion, 35...first surface, 36...second surface, 37...first portion (first portion arranged on the inner peripheral side), 38...second portion (inclined surface, second portion arranged on the outer peripheral side), 40...tubular portion, PO...axial center (axial center of the hub portion), P15...position of the tip of the inclined surface, U...U-axis direction (radial direction), X...X-axis direction, Y...Y-axis direction, Z...Z-axis direction (axial direction).

Claims

1. An axial flow fan comprising: a casing having an intake port and an exhaust port, with a flow passage formed therein communicating from the intake port to the exhaust port; and an impeller disposed within the casing and rotatable about an axis, the impeller comprising a hub portion and a plurality of moving blades formed on the hub portion, the plurality of moving blades having a leading edge portion disposed on the intake port side and a trailing edge portion disposed on the exhaust port side, the trailing edge portion including a first portion disposed on the inner circumference side and a second portion disposed on the outer circumference side, the second portion including an inclined surface inclined at an angle different from that of the first portion, and the inclined surface of the second portion being inclined such that a blade thickness in the second portion is thinner than the blade thickness of the first portion.

2. An axial flow fan as set forth in claim 1, wherein the trailing edge of said second portion is located closer to said leading edge portion than the trailing edge of said first portion in the rotational direction of said impeller.

3. An axial fan as claimed in claim 1 or 2, wherein the plurality of blades have a first surface arranged on the intake port side in the axial direction, and a second surface arranged on the exhaust port side in the axial direction, the first surface includes a first region on a leading edge side of the blade and a second region on a trailing edge side of the blade, the second portion has the second region, the second region of the first surface includes the inclined surface, the inclined surface being inclined at a different angle relative to the first region, and the inclined surface of the second region is inclined so as to be thinner than the blade thickness in the first region.

4. An axial fan as described in claim 3, wherein the inclination angle of the second region relative to the first region is greater than or equal to 2 degrees and less than 20 degrees when viewed from a radial direction connecting two points which are at the same position in the axial direction of the hub portion and connecting the axis of the hub portion and the position of the tip of the inclined surface of the second portion at the outer peripheral edge of the blade.

5. An axial fan as claimed in any one of claims 1 to 4, wherein the length of said second portion in the axial direction is 5% or more and 35% or less of the length from the leading edge to the trailing edge at the outer periphery of said plurality of blades.

6. An axial fan as claimed in any one of claims 1 to 5, wherein the length of the second portion at the outer circumferential edge of the plurality of blades in the direction of rotation of the impeller is equal to or greater than 5% and equal to or less than 35% of the total length of the outer circumferential edge.

7. An axial fan according to any one of claims 1 to 6, wherein the length of said second portion at said trailing edge in the direction in which said trailing edge extends is equal to or greater than 10% and equal to or less than 100% of the total width of said plurality of blades.

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