Axial flow fan

Abstract

The axial flow fan includes: a hub portion (31) to which a rotating shaft (20) is attached; and five or fewer blades (41) provided on the hub portion (31). The blade (41) includes: a leading edge (45) in front of the rotating direction of the rotating shaft (20); trailing edges (46, 71) behind the rotating direction of the rotating shaft (20); and a porous portion (61). If the dimension from the leading edge (45) to the trailing edges (46, 71) is defined as the blade chord length (L1), the porous portion (61) is disposed at a position behind the leading edge (45) and reaching 40% or more of the blade chord length (L1).

Description

Technical Field

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

[0002] An axial flow fan includes a hub and blades provided on the hub. A rotating shaft is installed on the hub. As the rotating shaft rotates, the hub and the blades rotate. The pressure fluctuation caused by the rotation of the blades causes noise generation. The blades disclosed in Patent Document 1 have a porous portion. By providing the porous portion, the difference in pressure between the positive pressure side and the negative pressure side of the blade becomes smaller. Thereby, it is possible to suppress pressure fluctuations and suppress noise generation.

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Patent No. 2754862 Summary of the Invention

[0006] Problems to be Solved by the Invention

[0007] Since a porous portion is provided in the blade, the strength of the blade may be reduced.

[0008] Means for Solving the Problems

[0009] The axial flow fan for solving this problem includes: a hub on which a rotating shaft is installed; and five or fewer blades provided on the hub, the blades having: a leading edge, which is in front of the rotating direction of the rotating shaft; a trailing edge, which is behind the rotating direction of the rotating shaft; and a porous portion, and if the dimension from the leading edge to the trailing edge is defined as the blade chord length, the porous portion is arranged at a position 40% or more behind from the leading edge up to the blade chord length.

[0010] When the number of blades is five or fewer, noise is likely to be generated on the trailing edge side of the blade. By arranging the porous portion at a position 40% or more behind from the leading edge up to the blade chord length, the noise generated on the trailing edge side of the blade is reduced. By providing the porous portion at a position close to the noise source, compared with the case where the porous portion is provided throughout the entire blade, the porous portion can be reduced. Thereby, a reduction in the strength of the blade can be suppressed.

[0011] In the above axial flow fan, the blade includes: an inner peripheral edge that engages with the hub portion; and an outer peripheral edge that extends in the rotational direction of the rotating shaft between the leading edge and the trailing edge. The trailing edge includes: an inner peripheral connecting portion that connects to the inner peripheral edge; and an outer peripheral connecting portion that connects to the outer peripheral edge; a first portion that extends from the inner peripheral connecting portion toward the leading edge; a second portion that extends from the outer peripheral connecting portion toward the leading edge; and a curved third portion that connects the first portion and the second portion. When the length of the orbit in the rotational direction from the leading edge to the central position of the third portion is set as a first distance, and the length of the orbit in the rotational direction from the leading edge to the intersection point of the imaginary line connecting the first portion and the second portion and the orbit is set as a second distance, the first distance is 95% or less of the second distance. If the range obtained by extending the circular range with a radius of the radius of the third portion + 5 mm and centered on the central position of the third portion in the rotational direction is set as a non-setting range, the porous portion is provided at a position different from the non-setting range.

[0012] Stress is likely to concentrate on the third portion. If the distance between the third portion and the porous portion is short, the strength of the blade may be reduced. Correspondingly, the range obtained by extending the circular range with a radius of the radius of the third portion + 5 mm and centered on the central position of the third portion in the rotational direction is set as a non-setting range, and the porous portion is provided at a position different from the non-setting range. Thereby, compared with the case where the porous portion is provided in the non-setting range, a reduction in the strength of the blade can be suppressed.

[0013] In the above axial flow fan, the blade includes: an inner peripheral edge that engages with the hub portion; and an outer peripheral edge that extends in the rotational direction of the rotating shaft between the leading edge and the trailing edge. The porous portion is disposed to be biased toward the outer peripheral edge with respect to the central position between the inner peripheral edge and the outer peripheral edge.

[0014] The relative velocity of the air flow is faster the closer it is to the outer peripheral edge. The faster the relative velocity of the air flow, the more likely it is to cause noise. By disposing the porous portion to be biased toward the outer peripheral edge with respect to the central position between the inner peripheral edge and the outer peripheral edge, noise can be suppressed.

[0015] In the above axial flow fan, the area of the porous portion is 30% or less with respect to the total area of the positive pressure surface of the blade.

[0016] The axial flow fan for solving this problem includes: a hub to which a rotating shaft is attached; and blades provided on the hub. The blades include: a leading edge at the front in the rotation direction of the rotating shaft; a trailing edge at the rear in the rotation direction of the rotating shaft; and an inner peripheral edge that engages with the hub; an outer peripheral edge that extends in the rotation direction of the rotating shaft between the leading edge and the trailing edge; and a porous portion. The trailing edge includes: an inner peripheral connecting portion that connects to the inner peripheral edge; an outer peripheral connecting portion that connects to the outer peripheral edge; a first portion that extends from the inner peripheral connecting portion toward the leading edge; a second portion that extends from the outer peripheral connecting portion toward the leading edge; and a curved third portion that connects the first portion and the second portion. When the length of the track in the rotation direction from the leading edge to the center position of the third portion is set as a first distance, and the length of the track in the rotation direction from the leading edge to the intersection of the imaginary line connecting the first portion and the second portion and the track is set as a second distance, the first distance is 95% or less of the second distance. If a range in a circular shape with a radius of the radius of the third portion + 5 mm and centered on the center position of the third portion is extended in the rotation direction to obtain a non - setting range, the porous portion is provided at a position different from the non - setting range.

[0017] Stress is likely to concentrate on the third portion. If the distance between the third portion and the porous portion is short, the strength of the blade may be reduced. By providing the porous portion at a position different from the non - setting range, compared with the case where the porous portion is provided in the non - setting range, a reduction in the strength of the blade can be suppressed.

[0018] The axial flow fan for solving this problem has: a hub to which a rotating shaft is attached; and six or more blades provided on the hub. The blades have: a leading edge at the front in the rotation direction of the rotating shaft; a trailing edge at the rear in the rotation direction of the rotating shaft; and a porous portion. If the dimension from the leading edge to the trailing edge is set as the blade chord length, the porous portion is arranged at a position that reaches 60% or more forward from the trailing edge.

[0019] When there are six or more blades, noise is likely to be generated on the leading - edge side of the blades. By arranging the porous portion at a position that reaches 60% or more forward from the trailing edge, the noise generated on the leading - edge side of the blades is reduced. By providing the porous portion at a position close to the noise source, compared with the case where the porous portion is provided throughout the entire blade, the amount of the porous portion can be reduced. Thereby, a reduction in the strength of the blade can be suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a schematic structural diagram of an air conditioner.

[0021] Figure 2 This is a front view of the axial flow fan of the first embodiment as viewed from the positive pressure surface side.

[0022] Figure 3 This is a cross-sectional view of the blade of the first embodiment along the Figure 2 section line 3-3.

[0023] Figure 4 This is an enlarged view of the blade of the first embodiment.

[0024] Figure 5 This is a graph showing the relationship between the sound pressure level of the noise generated by the rotation of the axial flow fan and the position of the porous part.

[0025] Figure 6 This is a graph showing the sound pressure level of each frequency of the axial flow fan without a porous part and the axial flow fan of the first embodiment.

[0026] Figure 7 This is a front view of the axial flow fan of the second embodiment as viewed from the positive pressure surface side.

[0027] Figure 8 This is an enlarged view of the blade of the second embodiment.

[0028] Figure 9 This is a front view of the axial flow fan of the third embodiment as viewed from the positive pressure surface side.

[0029] Figure 10 This is an enlarged view of the blade of the third embodiment. Detailed implementation manners

[0030] <First Embodiment>

[0031] The first embodiment of the axial flow fan will be described.

[0032] <Air conditioner>

[0033] As Figure 1 shown, the air conditioner 10 includes an outdoor unit 11, an indoor unit 21, and pipes 24 and 25. The outdoor unit 11 includes stop valves 12 and 13, a compressor 14, a four-way valve 15, an outdoor heat exchanger 16, an expansion valve 17, a liquid receiver 18, an axial flow fan 30, and a fan motor 19. The indoor unit 21 includes an indoor heat exchanger 22 and an indoor fan 23.

[0034] Pipes 24 and 25 connect the outdoor unit 11 and the indoor unit 21. Pipes 24 and 25 are connected to the stop valves 12 and 13. The indoor unit 21 is connected to the outdoor unit 11 through pipes 24 and 25, so that the air conditioner 10 has a refrigerant circuit 26. The refrigerant circuit 26 is a circuit for the refrigerant to flow. The refrigerant circuit 26 includes a compressor 14, a four-way valve 15, an outdoor heat exchanger 16, an expansion valve 17, a liquid receiver 18, and an indoor heat exchanger 22.

[0035] During the cooling operation of the air conditioner 10, the four-way valve 15 is switched so that the refrigerant discharged from the compressor 14 flows to the outdoor heat exchanger 16. In the outdoor heat exchanger 16, heat exchange occurs between the outdoor air and the refrigerant. The refrigerant deprived of heat by the outdoor heat exchanger 16 is decompressed by the expansion valve 17. The refrigerant decompressed by the expansion valve 17 flows to the indoor heat exchanger 22. In the indoor heat exchanger 22, heat exchange occurs between the indoor air and the refrigerant. The refrigerant that has obtained heat from the indoor air in the indoor heat exchanger 22 is sucked into the compressor 14 through the four-way valve 15 and the liquid receiver 18. The indoor air deprived of heat through the heat exchange in the indoor heat exchanger 22 is used to cool the indoor space. The outdoor air is supplied to the outdoor heat exchanger 16 by the axial flow fan 30. The indoor air is supplied to the indoor heat exchanger 22 by the indoor fan 23.

[0036] During the heating operation of the air conditioner 10, the four-way valve 15 is switched so that the refrigerant discharged from the compressor 14 flows to the indoor heat exchanger 22. In the indoor heat exchanger 22, heat exchange occurs between the indoor air and the refrigerant. The refrigerant that has released heat in the indoor heat exchanger 22 is decompressed by the expansion valve 17. The refrigerant decompressed by the expansion valve 17 flows to the outdoor heat exchanger 16. In the outdoor heat exchanger 16, heat exchange occurs between the outdoor air and the refrigerant. The refrigerant that has obtained heat from the outdoor air in the outdoor heat exchanger 16 is sucked into the compressor 14 through the four-way valve 15 and the liquid receiver 18. The indoor air that has obtained heat through the heat exchange in the indoor heat exchanger 22 is used to heat the indoor space.

[0037] <Axial flow fan>

[0038] As Figure 2 shown, the axial flow fan 30 includes a hub portion 31 and five or fewer blades 41.

[0039] The hub portion 31 is cylindrical. The hub portion 31 is made of resin, for example. The hub portion 31 has an insertion hole 32 and an outer peripheral surface 33. The insertion hole 32 is provided at the radial center of the hub portion 31. The rotating shaft 20 of the fan motor 19 is inserted into the insertion hole 32. The axial flow fan 30 rotates by the rotation of the rotating shaft 20. The rotating shaft 20 rotates in one direction. In the following description, the rotation direction refers to the direction in which the rotating shaft 20 rotates.

[0040] The blade 41 is three in number. The blade 41 can also be five, four or two in number. The blade 41 is provided on the outer peripheral surface 33 of the hub portion 31. The blade 41 extends radially from the outer peripheral surface 33 along the hub portion 31. The radial direction of the hub portion 31 is the direction orthogonal to the rotation axis 20. The blades 41 are arranged at intervals from each other in the rotation direction. The three blades 41 have the same shape. In the following description, the radial direction refers to the radial direction of the hub portion 31.

[0041] As Figure 3 shown, the blade 41 has a pressure surface 42 and a suction surface 43. The pressure surface 42 is the blade surface that becomes the positive pressure side due to the air flow when the axial flow fan 30 rotates. The suction surface 43 is the blade surface that becomes the negative pressure side due to the air flow when the axial flow fan 30 rotates. The pressure surface 42 is the surface from which air flows out when the axial flow fan 30 rotates. The suction surface 43 is the surface into which air flows in when the axial flow fan 30 rotates.

[0042] As Figure 2 shown, the blade 41 has a main body 44 and a porous portion 61. The main body 44 is made of resin, for example. The hub portion 31 and the main body 44 are integrally formed. The hub portion 31 and the main body 44 are integrally formed by injection molding, for example.

[0043] The main body 44 has a leading edge 45, a trailing edge 46, an inner peripheral edge 47 and an outer peripheral edge 48. The leading edge 45 is the edge at the front in the rotation direction. The trailing edge 46 is the edge at the rear in the rotation direction. The leading edge 45 is curved. The leading edge 45 is curved in an arc shape so as to be recessed toward the trailing edge 46. The trailing edge 46 is curved. The trailing edge 46 is curved in an arc shape so as to be away from the leading edge 45. The inner peripheral edge 47 is joined to the hub portion 31. The inner peripheral edge 47 extends between the leading edge 45 and the trailing edge 46. The outer peripheral edge 48 extends between the leading edge 45 and the trailing edge 46. The radial dimension from the rotation axis 20 to the inner peripheral edge 47 is shorter than the radial dimension from the rotation axis 20 to the outer peripheral edge 48. The outer peripheral edge 48 is curved. The outer peripheral edge 48 is curved in an arc shape so as to protrude in the radial direction.

[0044] As Figure 4 shown, the dimension from the leading edge 45 to the trailing edge 46 is defined as the blade chord length L1. Specifically, the dimension of the imaginary line connecting the portions having the same radial dimension from the rotation axis 20 between the leading edge 45 and the trailing edge 46 is defined as the blade chord length L1. When drawing a circle centered on the rotation axis 20, the blade chord length L1 can also be said to be the length of the arc extending between the leading edge 45 and the trailing edge 46 of the same blade 41. In Figure 4 , as an example, three blade chord lengths L1 are illustrated. The blade chord length L1 may be of different dimensions depending on the position of the blade 41 in the radial direction.

[0045] As Figure 3As shown, the portion between the center position C1 of the blade chord length L1 and the leading edge 45 is defined as the leading edge portion 51, and the portion between the center position C1 of the blade chord length L1 and the trailing edge 46 is defined as the trailing edge portion 52. The leading edge portion 51 is heavier than the trailing edge portion 52. For example, as Figure 3 shown, by making the main body 44 gradually thicker from the trailing edge 46 toward the leading edge 45, the leading edge portion 51 is heavier than the trailing edge portion 52. It is also possible to make the leading edge portion 51 heavier than the trailing edge portion 52 by making the thickness of a part of the leading edge portion 51 thicker than that of the trailing edge portion 52.

[0046] The porous portion 61 is made of synthetic resin or ceramic. The strength of the porous portion 61 is lower than that of the main body 44. The porous portion 61 is provided in the region surrounded by the leading edge 45, the trailing edge 46, the inner peripheral edge 47, and the outer peripheral edge 48. The porous portion 61 is integrally surrounded by the main body 44 having a strength higher than that of the porous portion 61. The porous portion 61 has holes extending between the pressure side 42 and the suction side 43. The average pore diameter of the porous portion 61 is, for example, 700 [μm] or less. The thickness of the porous portion 61 is, for example, 5 [mm] or less. The porous portion 61 is provided integrally with the main body 44. The porous portion 61 and the main body 44 are integrally provided, for example, by insert molding, bonding, or fitting.

[0047] The porous portion 61 has a quadrilateral shape. Specifically, the porous portion 61 has a rounded quadrilateral shape with four corners curved.

[0048] As Figure 4 shown, the distance from the leading edge 45 to the porous portion 61 is defined as the arrangement distance L2. Specifically, the dimension of the imaginary line connecting the portions having the same radial dimension from the rotation axis 20 between the leading edge 45 and the porous portion 61 is defined as the arrangement distance L2. Among the portions having the same radial dimension from the rotation axis 20, the relationship L2 / blade chord length L1 ≥ 40% holds. It can be said that the porous portion 61 is arranged at a position more than 40% of the blade chord length L1 rearward from the leading edge 45. In Figure 4 the boundary line L11 indicating the position 40% of the blade chord length L1 from the leading edge 45 is shown. The portion between the leading edge 45 and the boundary line L11 is defined as the first region 53. The portion between the first region 53 and the trailing edge 46 is defined as the second region 54. The boundary line L11 is included in the second region 54. The porous portion 61 is provided only in the second region 54. The porous portion 61 is not provided in the first region 53. It can be said that the porous portion 61 is arranged biased toward the trailing edge 46. That is, the porous portion 61 included in the trailing edge portion 52 is more than the porous portion 61 included in the leading edge portion 51.

[0049] In addition, in the present embodiment, as the radial position changes from the rotation axis 20, both the arrangement distance L2 and the blade chord length L1 change. In this case, the porous portion 61 of the present embodiment is arranged at a position where the arrangement distance L2 / blade chord length L1 ≥ 40% regardless of the radial position from the rotation axis 20.

[0050] The porous portion 61 is provided to suppress the noise generated by the rotation of the axial flow fan 30. The noise reduction effect of the porous portion 61 varies depending on the arrangement position of the porous portion 61.

[0051] As Figure 5 shown, it can be seen that as the arrangement distance L2 / blade chord length L1 [%] increases, the sound pressure level [dBA] of the noise generated by the axial flow fan 30 decreases. In particular, if the arrangement distance L2 / blade chord length L1 is 40% or more, the sound pressure level decreases significantly.

[0052] As Figure 4 shown, the radial distance from the inner peripheral edge 47 to the outer peripheral edge 48 is defined as the first blade length R1. The radial distance from the inner peripheral edge 47 to the center position C2 of the porous portion 61 is defined as the second blade length R2. The center position C2 of the porous portion 61 is the radial center position. The second blade length R2 / first blade length R1 > 50% holds. The porous portion 61 is arranged offset toward the outer peripheral edge 48 from the center position between the inner peripheral edge 47 and the outer peripheral edge 48. Assuming that the blade 41 is divided into an inner peripheral region 55 and an outer peripheral region 56 with the radial center position of the blade 41 as the boundary. The inner peripheral region 55 is a region closer to the hub portion 31 than the outer peripheral region 56. In this case, the porous portion 61 included in the outer peripheral region 56 is more than the porous portion 61 included in the inner peripheral region 55.

[0053] The area of the main body 44 in the pressure surface 42 is larger than the area of the porous portion 61. In the present embodiment, the area of the porous portion 61 is 30% or less with respect to the entire area of the pressure surface 42.

[0054] <Function of the First Embodiment>

[0055] The longer the blade chord length L1 is, the more likely it is to generate noise on the trailing edge 46 side of the blade 41. When the number of blades 41 is five or less, in order to ensure the workload, the blade chord length L1 is likely to be long. Therefore, when the number of blades 41 is five or less, it is easy to generate noise on the trailing edge 46 side of the blade 41. If a pressure fluctuation occurs, noise is generated due to the pressure fluctuation. When a pressure fluctuation occurs, air moves between the pressure surface 42 side and the negative pressure surface 43 side via the porous portion 61, thereby suppressing the pressure fluctuation. In particular, by arranging the porous portion 61 at a position 40% or more behind the leading edge 45 up to the blade chord length L1, the pressure fluctuation is suppressed on the trailing edge 46 side of the blade 41.

[0056] Figure 6 This is a graph that decomposes the sound generated by the rotation of the axial flow fan 30 by frequency and correlates the sound pressure level of the sound with each frequency. From Figure 6 it can be seen that, compared with the axial flow fan without the porous portion 61, in the axial flow fan 30 of the present embodiment, the sound pressure level is reduced. In particular, it is possible to grasp that the reduction in the sound pressure level is significant at frequencies where the sound pressure level tends to increase.

[0057] <Effects of the First Embodiment>

[0058] The effects of the first embodiment will be described.

[0059] (1-1) The porous portion 61 is arranged at a position behind the leading edge 45 by more than 40% of the blade chord length L1. By arranging the porous portion 61 at a position where noise is likely to be generated, compared with the case where the porous portion 61 is arranged over the entire blade 41, the porous portion 61 can be reduced. Thereby, a decrease in the strength of the blade 41 can be suppressed.

[0060] Even when the porous portion 61 is reduced, by arranging the porous portion 61 at a position where noise is likely to be generated, the noise generated by the rotation of the axial flow fan 30 can be suppressed. A decrease in the strength of the blade 41 can be suppressed, and a noise reduction effect brought about by arranging the porous portion 61 can be obtained.

[0061] (1-2) The porous portion 61 is arranged biased toward the outer peripheral edge 48. The relative speed of the air flow is faster the closer it is to the outer peripheral edge 48. The faster the relative speed of the air flow, the more likely it is to be a cause of noise generation. By arranging the porous portion 61 biased toward the outer peripheral edge 48, the generation of noise can be suppressed.

[0062] (1-3) The area of the main body 44 in the positive pressure surface 42 is larger than the area of the porous portion 61. The blade 41 is mainly composed of the main body 44, and the porous portion 61 is provided locally. By locally using the porous portion 61 having a lower strength than the main body 44, a decrease in the strength of the blade 41 can be suppressed. In particular, by making the area of the porous portion 61 30% or less with respect to the entire area of the positive pressure surface 42, a decrease in the strength of the blade 41 can be appropriately suppressed.

[0063] (1-4) Since the leading edge portion 51 is heavier than the trailing edge portion 52, stress is likely to concentrate on the leading edge portion 51 when the axial flow fan 30 rotates. If the porous portion 61 is provided at the leading edge portion 51, that is, the porous portion 61 is provided at a position where stress is likely to concentrate, there may be insufficient strength at the leading edge portion 51. By providing the porous portion 61 in the second region 54, it is difficult for the porous portion 61 to be provided at the leading edge portion 51. Therefore, insufficient strength at the leading edge portion 51 can be suppressed.

[0064] (1-5) The axial flow fan 30 is used in the air conditioner 10. In order to improve the energy-saving performance, sometimes a large air volume is required for the air conditioner 10. In order to achieve a large air volume, it is necessary to increase the rotational speed of the axial flow fan 30 and enlarge the axial flow fan 30. In this case, the required strength of the axial flow fan 30 becomes higher. However, if the porous part 61 is reduced in order to improve the strength of the axial flow fan 30, the noise may become larger. As in the embodiment, by providing the porous part 61 at the part where noise is likely to be generated, the noise suppression effect can be obtained with a small amount of the porous part 61. It is possible to achieve both ensuring the strength required for the axial flow fan 30 and the effect of suppressing noise.

[0065] <Second Embodiment>

[0066] The second embodiment of the axial flow fan will be described. In the second embodiment, the points different from the first embodiment will be described. For the components that are the same as those in the first embodiment, the same names are given and the description is omitted.

[0067] As Figure 7 shown, the trailing edge 71 of the axial flow fan 70 includes an inner peripheral connecting portion 72, an outer peripheral connecting portion 73, and a notch dividing portion 74.

[0068] The inner peripheral connecting portion 72 is connected to the inner peripheral edge 47. The inner peripheral connecting portion 72 extends between the inner peripheral edge 47 and the notch dividing portion 74. The inner peripheral connecting portion 72 inclines rearward as it goes from the inner peripheral edge 47 toward the notch dividing portion 74.

[0069] The outer peripheral connecting portion 73 is connected to the outer peripheral edge 48. The outer peripheral connecting portion 73 extends between the outer peripheral edge 48 and the notch dividing portion 74. The outer peripheral connecting portion 73 inclines rearward as it goes from the outer peripheral edge 48 toward the notch dividing portion 74.

[0070] The notch dividing portion 74 is provided between the inner peripheral connecting portion 72 and the outer peripheral connecting portion 73. The notch dividing portion 74 connects the inner peripheral connecting portion 72 and the outer peripheral connecting portion 73. The notch dividing portion 74 includes a first portion 75, a second portion 76, and a third portion 77.

[0071] The first portion 75 is connected to the inner peripheral connecting portion 72. The first portion 75 extends from the inner peripheral connecting portion 72 toward the leading edge 45. The first portion 75 inclines in such a way that it approaches the outer peripheral edge 48 as it moves away from the inner peripheral connecting portion 72.

[0072] The second portion 76 is connected to the outer peripheral connecting portion 73. The second portion 76 extends from the outer peripheral connecting portion 73 toward the leading edge 45. The second portion 76 inclines in such a way that it approaches the inner peripheral edge 47 as it moves away from the outer peripheral connecting portion 73. The first portion 75 and the second portion 76 get closer to each other as they approach the leading edge 45.

[0073] The third part 77 connects the first part 75 and the second part 76. The third part 77 is bent in a manner that is recessed toward the leading edge 45. The area surrounded by the first part 75, the second part 76, and the third part 77 is the notch 78. The notch dividing part 74 divides and forms the notch 78. The notch 78 is provided for the purpose of improving the air volume and noise. The notch 78 is a space extending between the positive pressure surface 42 and the negative pressure surface 43. The notch 78 is recessed toward the leading edge 45.

[0074] As Figure 8 shown, a hypothetical line passing through the center position P1 of the third part 77 and extending in the rotational direction is defined as the orbit L12. The length of the orbit L12 from the leading edge 45 to the center position P1 of the third part 77 is defined as the first distance L3. The center position P1 of the third part 77 is the part in the notch dividing part 74 that is closest to the leading edge 45.

[0075] The point where the hypothetical line segment L13 connecting the first part 75 and the second part 76 intersects the orbit L12 is defined as the intersection point P2. The length of the orbit L12 from the leading edge 45 to the intersection point P2 is defined as the second distance L4. The line segment L13 connects the part P3 in the first part 75 that is closest to the inner peripheral edge 47 and the part P4 in the second part 76 that is closest to the outer peripheral edge 48. The first distance L3 is 95% or less of the second distance. The notch 78 can also be said to be recessed in such a way that the center position P1 is located more forward than the intersection point P2 by more than 5% of the second distance L4.

[0076] The blade 41 has a non - setting range A1. The non - setting range A1 is included in the following range: the range that includes the orbit L12 and is obtained by extending the notch 78 in the rotational direction. The non - setting range A1 in this embodiment is the range obtained by extending a circular range C3 with a radius R4 of the radius R3 + 5mm of the third part 77 and with the center position P1 of the third part 77 as the center in the rotational direction. The non - setting range A1 is a range that expands toward both the inner peripheral edge 47 and the outer peripheral edge 48 with the orbit L12 as the center.

[0077] The porous part 61 is provided at a position different from the non - setting range A1. In this embodiment, the porous part 61 is provided between the non - setting range A1 and the inner peripheral edge 47. The porous part 61 can also be provided between the non - setting range A1 and the outer peripheral edge 48. The porous part 61 is provided in a manner that does not overlap with the orbit L12.

[0078] The porous part 61 is arranged at a distance greater than a specified distance from the central position P1. Stress is likely to concentrate on the notch dividing part 74. In particular, stress is likely to concentrate on the central position P1. Therefore, the porous part 61 is arranged at a distance greater than a specified distance from the central position P1. In the present embodiment, a notch part 62 is provided in the porous part 61. The notch part 62 is provided at the corner of the four corners of the porous part 61 that is closest to the central position P1. The notch part 62 is a part formed by cutting the corner. By providing the notch part 62, the porous part 61 does not enter the range of a specified distance from the central position P1. Thereby, the porous part 61 is brought closer to the trailing edge 71, and the porous part 61 is prevented from approaching the central position P1 excessively. The notch part 62 is arranged in parallel with the first part 75. In addition, the above-mentioned specified distance may be greater than the radius R4, for example. However, it is not limited thereto, and the above-mentioned specified distance is arbitrary.

[0079] <Effects of the second embodiment>

[0080] The effects of the second embodiment will be described. In the second embodiment, in addition to the effects of the first embodiment, the following effects can also be obtained.

[0081] (2-1) Stress is likely to concentrate on the third part 77. If the distance between the third part 77 and the porous part 61 is short, the strength of the blade 41 may be reduced. By arranging the porous part 61 at a position different from the non-arrangement range A1, the reduction in the strength of the blade 41 can be suppressed compared with the case where the porous part 61 is arranged in the non-arrangement range A1.

[0082] <Third embodiment>

[0083] The third embodiment of the axial flow fan will be described. In the third embodiment, the points different from the first embodiment will be described. For the components that are the same as those in the first embodiment, the same names are given and the description is omitted.

[0084] As Figure 9 shown, the axial flow fan 80 includes six or more blades 81. Figure 9 The blades 81 shown are six in number. The number of blades 81 may also be seven or more. The six blades 81 have the same shape.

[0085] The blade 81 includes a main body 82 and a porous part 91. The main body 82 includes a leading edge 83, a trailing edge 84, an inner peripheral edge 85, and an outer peripheral edge 86.

[0086] As Figure 10As shown, the dimension from the leading edge 83 to the trailing edge 84 is defined as the blade chord length L5. The distance from the trailing edge 84 to the porous portion 91 is defined as the arrangement distance L6. At positions with the same radial dimension from the rotation axis 20, the relationship arrangement distance L6 / blade chord length L5 ≥ 60% holds. It can be said that the porous portion 91 is arranged at a position forward from the trailing edge 84 by more than 60% of the blade chord length L5. Figure 10 A hypothetical boundary line L14 is shown connecting the position that is 60% of the blade chord length L5 from the trailing edge 84. The area between the leading edge 83 and the boundary line L14 is defined as the first region 87. The area between the first region 87 and the trailing edge 84 is defined as the second region 88. The porous portion 91 is provided only in the first region 87. It can be said that the porous portion 91 is arranged offset toward the leading edge 83 from the center position of the blade chord length L5.

[0087] In addition, in the present embodiment, as the position changes in the rotation direction, the center position between the inner peripheral edge 85 and the outer peripheral edge 86 may change. The porous portion 91 of the present embodiment is arranged offset toward the outer peripheral edge 48 from the center position between the inner peripheral edge 85 and the outer peripheral edge 86 regardless of the position in the rotation direction.

[0088] <Function of the Third Embodiment>

[0089] The shorter the blade chord length L5 is, the easier it is to generate noise on the leading edge 83 side of the blade 81. When there are six or more blades 81, from the viewpoint of the moldability of the axial flow fan 80 and to ensure the flow path between the blades 81, the blade chord length L5 is likely to be short. Thus, when there are six or more blades 81, it is easy to generate noise on the leading edge 83 side of the blade 81. The porous portion 91 is arranged at a position forward from the trailing edge 84 by more than 60% of the blade chord length L5. Thus, the porous portion 91 is provided at the portion where noise is likely to be generated. The noise generated on the leading edge 83 side of the blade 81 is suppressed.

[0090] <Effect of the Third Embodiment>

[0091] The effect of the third embodiment will be described. In the third embodiment, in addition to the effects (1-2), (1-3), and (1-5) of the first embodiment, the following effects can also be obtained.

[0092] (3-1) By providing the porous portion 91 at the portion where noise is likely to be generated, compared with the case where the porous portion 91 is provided throughout the entire blade 81, the amount of the porous portion 91 can be reduced. Thus, a decrease in the strength of the blade 81 can be suppressed.

[0093] Even when the amount of the porous portion 91 is reduced, by disposing the porous portion 91 at a portion where noise is likely to be generated, it is possible to suppress the noise generated by the rotation of the axial flow fan 80. It is possible to suppress a decrease in the strength of the blade 81 and obtain a noise reduction effect brought about by disposing the porous portion 91.

[0094] <Modification Example>

[0095] In addition to the above-described embodiments, the axial flow fan of the present disclosure may be, for example, a modification example shown below or a mode obtained by combining at least two non-contradictory modification examples.

[0096] · In the second embodiment, the porous portion 61 may be disposed at a position forward of a position that is 40% of the blade chord length L1 from the leading edge 45.

[0097] · In the second embodiment, the number of blades 41 may be six or more.

[0098] · In the third embodiment, the trailing edge 84 may also have a notch dividing portion.

[0099] As described above, the embodiments of the axial flow fan have been described. However, it should be understood that various changes in the mode and details can be made without departing from the gist and scope of the axial flow fan described in the claims.

[0100] <Supplementary Note>

[0101] The technical ideas that can be grasped from the respective embodiments and modification examples are described.

[0102] (1) An axial flow fan, comprising: a hub portion to which a rotating shaft is attached; and blades provided on the hub portion, the blades including: a leading edge that is forward in the rotation direction of the rotating shaft; a trailing edge that is rearward in the rotation direction of the rotating shaft; an inner peripheral edge that is joined to the hub portion; an outer peripheral edge that extends in the rotation direction of the rotating shaft between the leading edge and the trailing edge; and a porous portion, the trailing edge having a notch dividing portion that forms a notch cut toward the leading edge, and the porous portion being configured not to overlap with a track that passes through a portion of the notch dividing portion closest to the leading edge and extends in the rotation direction.

[0103] (2) An axial flow fan, comprising: a hub portion to which a rotating shaft is attached; and six or more blades provided on the hub portion, the blades including: a leading edge that is forward in the rotation direction of the rotating shaft; a trailing edge that is rearward in the rotation direction of the rotating shaft; and a porous portion, where if the dimension from the leading edge to the trailing edge is defined as the blade chord length, the porous portion is disposed to be biased toward the leading edge with respect to the center position of the blade chord length.

Claims

1. An axial flow fan, comprising: a hub portion (31) to which a rotating shaft (20) is attached; and less than five blades (41) provided on the hub portion (31), wherein the blade (41) includes: a leading edge (45) that is in front of the rotating direction of the rotating shaft (20); a trailing edge (71) that is behind the rotating direction of the rotating shaft (20); an inner peripheral edge (47) that engages with the hub portion (31); an outer peripheral edge (48) that extends in the rotating direction of the rotating shaft (20) between the leading edge (45) and the trailing edge (71); and a porous portion (61), wherein the trailing edge (71) includes: an inner peripheral connecting portion (72) that connects to the inner peripheral edge (47); an outer peripheral connecting portion (73) that connects to the outer peripheral edge (48); a first portion (75) that extends from the inner peripheral connecting portion (72) toward the leading edge (45); a second portion (76) that extends from the outer peripheral connecting portion (73) toward the leading edge (45); and a curved third portion (77) that connects the first portion (75) and the second portion (76), wherein when the length of the track (L12) in the rotating direction from the leading edge (45) to the center position (P1) of the third portion (77) is set as a first distance (L3), and the length of the track (L12) in the rotating direction from the leading edge (45) to the intersection point (P2) of the imaginary line segment (L13) connecting the first portion (75) and the second portion (76) and the track (L12) is set as a second distance (L4), the first distance (L3) is 95% or less of the second distance (L4), when the dimension from the leading edge (45) to the trailing edge (71) is set as the blade chord length (L1), the porous portion (61) is disposed at a position behind the leading edge (45) and reaching 40% or more of the blade chord length (L1), when the range (C3) in a circular shape with a radius of the radius of the third portion (77) + 5 mm and with the center position (P1) of the third portion (77) as the center is extended in the rotating direction to obtain a non - setting range (A1), the porous portion (61) is provided at a position different from the non - setting range (A1).

2. The axial flow fan according to claim 1, wherein the porous portion (61) is disposed biased toward the outer peripheral edge (48) with respect to the center position between the inner peripheral edge (47) and the outer peripheral edge (48).

3. The axial flow fan according to claim 1 or 2, wherein the area of the porous portion (61) is 30% or less of the total area of the positive pressure surface of the blade (41).

4. An axial flow fan, comprising: a hub portion (31) to which a rotating shaft (20) is attached; and blades (41) provided on the hub portion (31), wherein the blade (41) includes: a leading edge (45) that is in front of the rotating direction of the rotating shaft (20); A trailing edge (71), which is behind the rotation direction of the rotation axis (20); An inner peripheral edge (47), which engages with the hub portion (31); An outer peripheral edge (48), which extends in the rotation direction of the rotation axis (20) between the leading edge (45) and the trailing edge (71); and A porous portion (61), The trailing edge (71) includes: An inner peripheral connection portion (72), which is connected to the inner peripheral edge (47); An outer peripheral connection portion (73), which is connected to the outer peripheral edge (48); A first portion (75), which extends from the inner peripheral connection portion (72) toward the leading edge (45); A second portion (76), which extends from the outer peripheral connection portion (73) toward the leading edge (45); and A curved third portion (77), which connects the first portion (75) and the second portion (76), When the length of the track (L12) in the rotation direction from the leading edge (45) to the central position (P1) of the third portion (77) is set as a first distance (L3), and the length of the track (L12) in the rotation direction from the leading edge (45) to the intersection point (P2) of the imaginary line segment (L13) connecting the first portion (75) and the second portion (76) and the track (L12) is set as a second distance (L4), the first distance (L3) is 95% or less of the second distance (L4). If a range (A1) obtained by extending a circular range (C3) centered on the central position (P1) of the third portion (77) with a radius of the radius of the third portion (77) + 5 mm in the rotation direction is set as a non - setting range, the porous portion (61) is provided at a position different from the non - setting range (A1).

5. An axial - flow fan, which includes: A hub portion (31), to which a rotation axis (20) is mounted; and Six or more blades (81), which are provided on the hub portion (31), The blade (81) includes: A leading edge (83), which is in front of the rotation direction of the rotation axis (20); A trailing edge (84), which is behind the rotation direction of the rotation axis (20); and A porous portion (91), If the dimension from the leading edge (83) to the trailing edge (84) is set as the blade chord length (L5), the porous portion (91) is only disposed at a position that is 60% or more forward from the trailing edge (84) up to the blade chord length (L5).

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