Centrifugal Fan

Abstract

To provide a centrifugal fan which can suppress the generation of noise caused by a biased speed distribution of an airflow in the vicinity of an outlet of an inter-blade flow passage.SOLUTION: In a plurality of pieces of blades 32, a blade rear edge part 324 is formed so as to be located inside a fan radial direction Dr as progressing toward one side of a fan axial core direction Da. Also, in a centrifugal fan 18, Dsi / Dso being a ratio of an inside diameter Dsi of a side plate 34 with respect to an outside diameter Dso of the side plate 34 satisfies "0.5<Dsi / Dso<0.7". Therefore, in the centrifugal fan 18, a workload at a main plate 36 side which is performed by each blade 32 can be increased compared with that at the side plate 34 side. By this constitution, an airflow which is biased to the side plate 34 side in the middle of the inter-blade flow passage 32a can be drawn to the main plate 36 side once again in the vicinity of an outlet of the inter-blade flow passage 32a. As a result, a speed distribution of the airflow in the vicinity of an outlet of the inter-blade flow passage 32a can be made to approach a distribution having no bias of the fan axial core direction Da, and the low noise of the centrifugal fan 18 can be obtained.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a centrifugal fan that moves air by rotating. [Background technology]

[0002] The centrifugal fan described in Patent Document 1 includes multiple three-dimensional blades (i.e., vanes), a main plate, and a side plate. One end face in the span direction of each vane is fixed to the main plate, and the other end face in the span direction of each vane is fixed to the side plate.

[0003] Patent Document 1 points out as an issue that in a three-dimensional blade, the main flow of the intake air does not flow along the side plate but is instead biased toward the main plate, causing the intake air flow to have a biased velocity distribution, resulting in noise.

[0004] In contrast, in the centrifugal fan of Patent Document 1, each blade is formed so that the diameter of the blade trailing edge is larger on the main plate side than on the side plate side, which improves the distribution of main flow velocity between the blades and reduces noise, as described in Patent Document 1. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2009 / 139422 Summary of the Invention [Problem to be solved by the invention]

[0006] Generally, centrifugal fans are assumed to have various different fan inner / outer diameter ratios, which are the ratio obtained by dividing the suction diameter, which is the inner diameter of the side plate (i.e., the diameter of the intake hole of the centrifugal fan), by the outlet diameter (i.e., the outer diameter of the side plate). However, Patent Document 1 does not mention the fan inner / outer diameter ratios.

[0007] Furthermore, as the fan inner / outer diameter ratio becomes smaller, the air flow passage formed between the blades (in other words, the inter-blade flow passage) becomes longer. Therefore, in a centrifugal fan with a fan inner / outer diameter ratio that is small beyond a certain level, an air flow not described in Patent Document 1 occurs in the inter-blade flow passage.

[0008] Specifically, the air flow in the inter-blade passage separates from the rear surface of the side plate (i.e., the surface of the side plate facing the blade) near the intake hole and is biased toward the main plate, but then reattaches to the side plate midway through the inter-blade passage. As a result, at the outlet of the inter-blade passage, the air flow is biased toward the side plate, resulting in an air flow velocity distribution that is biased to one side in the axial direction of the fan. This causes noise to be generated due to the biased air flow velocity distribution near the outlet of the inter-blade passage. This was a new discovery by the inventors.

[0009] In view of the above, an object of the present invention is to provide a centrifugal fan capable of suppressing the generation of noise caused by biased air flow velocity distribution near the outlet of the inter-blade flow passage. [Means for solving the problem]

[0010] In order to achieve the above object, the centrifugal fan according to claim 1 comprises: A centrifugal fan that rotates around a fan axis (CL) to draw in air from one side in an axial direction (Da) of the fan axis and blows the drawn-in air outward in a radial direction (Dr) of the fan axis, A plurality of blades (32) arranged side by side around a fan axis and having a blade trailing edge portion (324) on the radially outer side; a side plate (34) formed with an intake hole (34a) through which air is drawn, the side plate being provided on one side of the plurality of blades in the axial direction and connected to each of the plurality of blades; a main plate (36, 43, 401) connected to each of the plurality of blades on the side opposite to the side plate side and extending in a radial direction; If the inner diameter of the side plate is Dsi and the outer diameter of the side plate is Dso, Dsi / Dso is 0.5 <Dsi / Dso<0.7であり、 The trailing edge portion of the blade is formed so as to be located more radially inward toward one side in the axial direction.

[0011] Here, in the inter-blade flow path which is an air flow path formed between the blades, the air flow, as described above, is biased toward one side in the axial direction so as to once separate from the side plate and then reattach to the side plate. On the other hand, in the centrifugal fan described above, since the trailing edge portion of the blade is formed so as to be located more radially inward toward one side in the axial direction, the amount of work on the main plate side performed by each blade is increased compared to the side plate side, and the air flow can be drawn back to the main plate side again near the outlet of the inter-blade flow path. As a result, for example, compared with the case where the trailing edge portion of the blade is parallel to the fan axis, the velocity distribution of the air flow near the outlet of the inter-blade flow path can be made closer to a distribution without axial bias, and it is possible to reduce the noise of the centrifugal fan.

[0012] Further, in the centrifugal fan described above, when the inner diameter of the side plate is Dsi and the outer diameter of the side plate is Dso, Dsi / Dso satisfies 0.5 < Dsi / Dso < 0.7. Therefore, for a centrifugal fan in which the air flow in the inter-blade flow path is biased toward the side plate side near the outlet of the inter-blade flow path if the trailing edge portion of the blade is temporarily parallel to the fan axis, the above-described configuration in which the trailing edge portion is located more radially inward toward one side in the axial direction can be used. Therefore, it is possible to use the configuration of the trailing edge portion so as to appropriately reduce the noise of the centrifugal fan.

[0013] Note that the reference numerals with parentheses attached to each component etc. indicate an example of the correspondence relationship between the component etc. and the specific components etc. described in the embodiments described later.

Brief Description of the Drawings

[0014] [Figure 1] It is a perspective view showing the appearance of the blower in the first embodiment. [Diagram 2] In the first embodiment, it is a longitudinal sectional view showing the blower cut along a plane including the fan axis, that is, a sectional view schematically showing the II-II section of FIG. 1. [Diagram 3]FIG. 2 is a plan view showing a centrifugal fan and a rotating shaft of the blower in the first embodiment, as viewed from one side to the other side in the fan axial direction. [Figure 4] FIG. 3 is a cross-sectional view showing the same cross section as FIG. [Diagram 5] FIG. 2 is a perspective view showing an extracted blade trailing edge portion and its periphery of a blade of the centrifugal fan in the first embodiment. [Figure 6] FIG. 11 is a cross-sectional view showing a cross section obtained by cutting a trailing edge portion and its periphery of a centrifugal fan blade in a plane perpendicular to the fan axis in the first embodiment, in which (a) shows the cross section at a portion of the trailing edge portion that connects to a side plate, and (b) shows the cross section at a portion of the trailing edge portion that connects to a main plate. [Figure 7A] FIG. 11 is a diagram showing the analysis results of a CFD simulation for confirming the action and effect of the first embodiment, and is a diagram showing the velocity distribution of the air flow in the inter-blade passage obtained when "Dsi / Dso=0.72". [Figure 7B] FIG. 7B is a diagram showing the analysis results of a CFD simulation similar to FIG. 7A, and is a diagram showing the velocity distribution of the air flow in the inter-blade passage obtained when "Dsi / Dso=0.68". [Figure 7C] FIG. 7B is a diagram showing the analysis results of a CFD simulation similar to FIG. 7A, and is a diagram showing the velocity distribution of the air flow in the inter-blade passage obtained when "Dsi / Dso=0.55". [Figure 7D] FIG. 7B is a diagram showing the analysis results of a CFD simulation similar to FIG. 7A, and is a diagram showing the velocity distribution of the air flow in the inter-blade passage obtained when "Dsi / Dso=0.48". [Figure 8] FIG. 1 is a diagram in which the SPL of noise generated by the fan of the first embodiment is indicated by a solid line S1, and the SPL of noise generated by the fan of the comparative example is indicated by a dashed line S2. [Figure 9] FIG. 4 is a diagram comparing the noise generated by the fan of the first embodiment and the noise generated by the fan of the comparative example in terms of overall values. [Figure 10]FIG. 11 is a diagram showing the relationship between noise reduction effect and Dmo / Db2, which is the ratio of the outer diameter Dmo of the main plate to the other-side diameter Db2 of the blade trailing edge portion, in the first embodiment. [Figure 11] FIG. 11 is a vertical cross-sectional view illustrating a schematic view of a blower according to a second embodiment, cut along a plane including a fan axis, and corresponds to FIG. 2. [Figure 12] FIG. 11 is a vertical cross-sectional view showing a schematic view of a blower in a third embodiment, cut along a plane including a fan axis, and corresponds to FIG. 2. [Figure 13] FIG. 11 is a vertical cross-sectional view illustrating a blower according to a fourth embodiment, cut along a plane including a fan axis, and corresponds to FIG. 2. [Figure 14] FIG. 11 is a vertical cross-sectional view illustrating a schematic view of a blower in a fifth embodiment, cut along a plane including a fan axis, and corresponds to FIG. 2. [Figure 15] FIG. 13 is a vertical cross-sectional view illustrating a blower according to a sixth embodiment, cut along a plane including a fan axis, and corresponds to FIG. 2. [Figure 16] FIG. 13 is a vertical cross-sectional view illustrating a schematic view of a blower in a seventh embodiment, cut along a plane including a fan axis, and corresponds to FIG. 2. [Figure 17] FIG. 13 is a vertical cross-sectional view illustrating a schematic view of a blower according to an eighth embodiment, cut along a plane including a fan axis, and corresponds to FIG. 2. [Figure 18] FIG. 13 is a vertical cross-sectional view showing a schematic view of a blower in a ninth embodiment, cut along a plane including a fan axis, and corresponds to FIG. 2. [Figure 19] FIG. 2 is a vertical cross-sectional view showing a schematic view of a blower in a tenth embodiment, cut along a plane including a fan axis. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, each embodiment will be described with reference to the drawings. In the following embodiments, the same reference numerals are given to parts that are the same or equivalent to each other.

[0016] (First embodiment) 1 and 2, the blower 10 of this embodiment is a centrifugal blower, more specifically a turbo blower. The blower 10 includes a casing 12 which is the housing of the blower 10, a rotating shaft 14, an electric motor 16, an electronic board 17, a centrifugal fan 18, a bearing 28, a bearing housing 29, and the like.

[0017] The fan axis CL shown in Fig. 2 is the center of rotation of the centrifugal fan 18. Arrow Da in Fig. 2 indicates the axial direction Da of the fan axis CL, i.e., the fan axial direction Da. Arrow Dr in Fig. 2 indicates the radial direction Dr of the fan axis CL, i.e., the fan radial direction Dr. In Fig. 2 and drawings equivalent to Fig. 2 described later, the right side of the fan axis CL is not shown in the drawing.

[0018] The casing 12 protects the electric motor 16, the electronic board 17, and the centrifugal fan 18 from dust and dirt outside the blower 10. To that end, the casing 12 houses the electric motor 16, the electronic board 17, and the centrifugal fan 18. The casing 12 is also composed of a first case member 22 and a second case member 24. The casing 12 is a non-rotating member of the blower 10 that does not rotate.

[0019] The first case member 22 of the casing 12 is made of, for example, resin, and has a generally disk-like shape with a larger diameter than the centrifugal fan 18. The first case member 22 is made up of a first cover portion 221, a first case outer periphery 222, a first peripheral edge portion 223, and a plurality of support columns 224.

[0020] The first case member 22 is a cover that covers the centrifugal fan 18 on one side in the fan axial direction Da relative to the centrifugal fan 18. Therefore, the first case member 22 is provided on the side opposite the blades 32 with respect to the side plate 34 of the centrifugal fan 18. In addition, since the centrifugal fan 18 rotates relative to the casing 12, the first case member 22 is disposed away from the side plate 34 of the centrifugal fan 18 to prevent mutual interference. The first case member 22 corresponds to the side plate adjacent case of the present disclosure.

[0021] The first cover portion 221 of the first case member 22 has a shape that expands in the fan radial direction Dr. The first cover portion 221 is disposed on one side of the centrifugal fan 18 in the fan axial direction Da, and covers one side of the centrifugal fan 18 in the fan axial direction Da.

[0022] An air intake port 221a is formed on the inner periphery of the first cover portion 221, penetrating the first cover portion 221 in the fan axial direction Da, and air is drawn into the centrifugal fan 18 through the air intake port 221a. The first cover portion 221 also has an intake port forming portion 221b provided as a bell mouth that forms the periphery of the air intake port 221a. The intake port forming portion 221b forms the air intake port 221a inside the intake port forming portion 221b, and smoothly guides air flowing into the air intake port 221a from the outside of the blower 10 into the air intake port 221a.

[0023] The first case outer periphery 222 of the first case member 22 is disposed outward in the fan radial direction Dr relative to the first cover part 221 and is connected to the first cover part 221. The first case outer periphery 222 is disposed outward in the fan radial direction Dr relative to the side plate 34 of the centrifugal fan 18. The first case outer periphery 222 corresponds to the case outer periphery of the present disclosure.

[0024] As shown in Figures 1 and 2, the first peripheral portion 223 of the first case member 22 is provided outside the first case outer circumferential portion 222 in the fan radial direction Dr, and forms the periphery of the first case member 22 around the fan axis CL.

[0025] The multiple pillars 224 of the first case member 22 each protrude from the first case outer circumferential portion 222 toward the inside of the casing 12 in parallel to the fan axis CL. The pillars 224 each have a thick-walled cylindrical shape with a central axis parallel to the fan axis CL. On the inside of the pillars 224, there is formed a screw hole through which a screw 26 that connects the first case member 22 and the second case member 24 is inserted.

[0026] Each support pillar 224 of the first case member 22 is disposed outward in the fan radial direction Dr from the centrifugal fan 18. The first case member 22 and the second case member 24 are joined together by screws 26 inserted into the support pillars 224 with the tips of the support pillars 224 abutting against the second case member 24.

[0027] The second case member 24 has a generally disk shape with generally the same diameter as the first case member 22. The second case member 24 is made of a metal such as iron or stainless steel or a resin, and also functions as a motor housing that covers the electric motor 16 and the electronic board 17. The second case member 24 is made up of a second cover portion 241, a second case outer periphery 242, and a second rim portion 243.

[0028] The second cover portion 241 is disposed on the other side of the centrifugal fan 18 and the electric motor 16 in the fan axial direction Da, and covers the other side of the centrifugal fan 18 and the electric motor 16 in the fan axial direction Da.

[0029] The second case outer peripheral portion 242 of the second case member 24 is disposed outward in the fan radial direction Dr relative to the second cover portion 241 and is connected to the second cover portion 241. The second case outer peripheral portion 242 is disposed outward of the main plate 36 of the centrifugal fan 18 in the fan radial direction Dr.

[0030] The second case outer peripheral portion 242 and the first case outer peripheral portion 222 are formed to face each other in the fan axial direction Da. A fan outer peripheral flow path 12b is formed between the second case outer peripheral portion 242 and the first case outer peripheral portion 222, which causes the air blown out from the air outlet 18a of the centrifugal fan 18 to flow outward in the fan radial direction Dr. This fan outer peripheral flow path 12b is formed around the entire circumference of the centrifugal fan 18.

[0031] The second peripheral portion 243 of the second case member 24 is provided outside the second case outer circumferential portion 242 in the fan radial direction Dr, and forms the periphery of the second case member 24 around the fan axis CL.

[0032] The first peripheral portion 223 and the second peripheral portion 243 constitute an air blowing portion that blows out air in the casing 12. The first peripheral portion 223 and the second peripheral portion 243 also form an air blowing outlet 12a, which blows out air blown out from the centrifugal fan 18, between the first peripheral portion 223 and the second peripheral portion 243 in the fan axial direction Da. This air blowing outlet 12a is also the downstream end of the air flow of the fan outer circumferential flow path 12b.

[0033] Specifically, the air outlet 12a is formed on the fan side surface of the blower 10 and opens facing outward in the fan radial direction Dr. The air outlet 12a opens around the entire circumference of the casing 12 centered on the fan axis CL and blows out air from the centrifugal fan 18. In other words, the blower 10 is an all-around blower in which the air outlet 12a is provided around the entire circumference of the casing 12. Note that, since the air blowing out from the casing 12 is prevented by the support pillar 224 at the location where the support pillar 224 is provided, the air outlet 12a opening around the entire circumference of the casing 12 includes the meaning that the air outlet 12a is opening around approximately the entire circumference.

[0034] The rotating shaft 14 is made of a metal such as iron, stainless steel, or brass. The rotating shaft 14 is a cylindrical rod as shown in FIG. 2, and is, for example, press-fitted into the inner ring of the bearing 28. Therefore, the rotating shaft 14 is fixed to the inner ring of the bearing 28. In addition, the outer ring of the bearing 28 is fixed to the bearing housing 29 by, for example, being press-fitted. The bearing housing 29 is made of a metal such as aluminum alloy, brass, iron, or stainless steel, and is fixed to the second cover portion 241.

[0035] Therefore, the rotating shaft 14 is supported by the second cover part 241 via the bearings 28. That is, the rotating shaft 14 is rotatable relative to the second cover part 241 about the fan axis CL.

[0036] At the same time, one end of the rotating shaft 14 in the fan axial direction Da is fitted into an inner circumferential hole 36a of a main plate 36 of the centrifugal fan 18, whereby the centrifugal fan 18 is fixed to the rotating shaft 14. In other words, the centrifugal fan 18 rotates integrally with the rotating shaft 14 around the fan axis CL.

[0037] The electric motor 16 is an outer rotor type brushless DC motor. The electric motor 16 is disposed, together with the electronic board 17, between the main plate 36 of the centrifugal fan 18 and the second cover part 241 in the fan axial direction Da. The electric motor 16 includes a motor rotor 161, a rotor magnet 162, and a motor stator 163. The motor rotor 161 is made of metal such as a steel plate, and is formed, for example, by press forming the steel plate.

[0038] The rotor magnet 162 is a permanent magnet, and is made of, for example, a rubber magnet containing ferrite, neodymium, etc. The rotor magnet 162 is fixed integrally to the motor rotor 161. The motor rotor 161 is also fixed to the rotor connection portion 38 of the centrifugal fan 18. In other words, the motor rotor 161 and the rotor magnet 162 rotate integrally with the centrifugal fan 18 around the fan axis CL.

[0039] The motor stator 163 includes a stator coil 163a and a stator core 163b electrically connected to the electronic board 17. The motor stator 163 is disposed radially inward from the rotor magnet 162 with a small gap therebetween. The motor stator 163 is fixed to the second cover portion 241 of the second case member 24 via the bearing housing 29. A plurality of electric components (not shown) are mounted on the electronic board 17, and for example, an electric circuit for rotating the electric motor 16 is configured on the electronic board 17.

[0040] In the electric motor 16 thus configured, when electricity is applied from an external power source to the stator coil 163a of the motor stator 163, the stator coil 163a generates a magnetic flux change in the stator core 163b. The magnetic flux change in the stator core 163b generates a force that attracts the rotor magnet 162. The motor rotor 161 is fixed to the rotating shaft 14 that is rotatably supported by the bearings 28, and therefore receives the force that attracts the rotor magnet 162 and rotates about the fan axis CL. In short, when electricity is applied to the electric motor 16, the centrifugal fan 18 to which the motor rotor 161 is fixed rotates about the fan axis CL.

[0041] The centrifugal fan 18 is an impeller applied to the blower 10, as shown in Figures 2 and 3. The centrifugal fan 18 blows air by rotating about the fan axis CL in a predetermined fan rotation direction DRf. That is, the centrifugal fan 18 rotates about the fan axis CL, thereby drawing in air through the air intake port 221a from one side of the fan axis direction Da, as indicated by the arrow FLa. The centrifugal fan 18 then blows out the drawn air radially outward of the centrifugal fan 18, as indicated by the arrow FLb.

[0042] Specifically, the centrifugal fan 18 of this embodiment is a turbofan. The centrifugal fan 18 has a plurality of blades 32, a side plate 34, a main plate 36, and a rotor connector 38. The centrifugal fan 18 is made of, for example, resin, and the plurality of blades 32, the side plate 34, the main plate 36, and the rotor connector 38 are integrally configured.

[0043] The blades 32 are arranged around the fan axis CL. More specifically, the blades 32 are arranged side by side in the circumferential direction Dc of the fan axis CL with gaps between them allowing air to flow. The blades 32 are also called fan blades.

[0044] Each of the blades 32 has a blade one end 321 provided on one side of the blade 32 in the fan axial direction Da, and a blade other end 322 provided on the other side of the blade 32 opposite to the one side in the fan axial direction Da. The plurality of blades 32 form inter-blade flow passages 32a through which air flows between adjacent blades 32 among the plurality of blades 32.

[0045] 2 and 3, the side plate 34 has a disk-like shape that expands in the fan radial direction Dr. An air intake hole 34a is formed on the radially inner side of the side plate 34, through which air is drawn from the air intake port 221a of the casing 12 as shown by the arrow FLa. Therefore, the side plate 34 has an annular shape centered on the fan axis CL.

[0046] Moreover, the side plate 34 has a side plate inner peripheral end 341 and a side plate outer peripheral end 342. The side plate inner peripheral end 341 is an end of the side plate 34 provided on the inside in the fan radial direction Dr, and forms an air intake hole 34a. The side plate outer peripheral end 342 is an end of the side plate 34 provided on the outside in the fan radial direction Dr. The side plate outer peripheral end 342 corresponds to the outer peripheral end of the side plate 34 according to the present disclosure.

[0047] Moreover, the side plate 34 is provided on one side of the plurality of blades 32 in the fan axial direction Da, i.e., on the air intake port 221a side. At the same time, the side plate 34 is connected to each of the plurality of blades 32. In other words, the side plate 34 is connected to each of the blades 32 at one blade end portion 321.

[0048] The side plate 34 also has a side plate other surface 343 facing the other side in the fan axial direction Da. This side plate other surface 343 faces the inter-blade flow passage 32a and guides the airflow inside the centrifugal fan 18. The side plate other surface 343 is a curved surface expanding in the fan radial direction Dr, and is positioned on the other side of the fan axial direction Da as it moves outward in the fan radial direction Dr. In the cross section of Figure 2, which is a vertical cross section including the fan axis CL, the radius of curvature of the side plate other surface 343 increases as it moves outward in the fan radial direction Dr.

[0049] For example, in this embodiment, in the vertical cross section of the blower 10 shown in Fig. 2, the side panel other surface 343 has an inner arc shape 343a, an outer arc shape 343b, and an outer linear shape 343c. The inner arc shape 343a, the outer arc shape 343b, and the outer linear shape 343c are smoothly connected in this order from the inside in the fan radial direction Dr. The radius of curvature R2 of the outer arc shape 343b is larger than the radius of curvature R1 of the inner arc shape 343a, and the outer linear shape 343c is a straight line perpendicular to the fan axis CL.

[0050] The main plate 36 is fixed to the rotating shaft 14 which is rotatable about the fan axis CL, and is therefore supported rotatably about the fan axis CL with respect to the casing 12. The main plate 36 has a disk-like shape which expands in the fan radial direction Dr with the fan axis CL as its center.

[0051] Further, the main plate 36 is connected to each of the plurality of blades 32 on the side opposite to the side plate 34. That is, the main plate 36 is connected to each of the plurality of blades 32 at the other blade end portion 322.

[0052] The main plate 36 also has a main plate guide surface 36b that guides the airflow in the centrifugal fan 18. The main plate guide surface 36b faces the inter-blade flow passage 32a and faces the side plate other surface 343 across the inter-blade flow passage 32a. The main plate guide surface 36b is a curved surface that faces one side of the fan axial direction Da and expands in the fan radial direction Dr, and is formed so as to be positioned on the other side of the fan axial direction Da as it moves outward in the fan radial direction Dr. Due to this shape, the main plate guide surface 36b guides the airflow that is sucked into the air intake port 221a and faces the fan axial direction Da to face outward in the fan radial direction Dr.

[0053] Further, in order to fix the main plate 36 to the rotating shaft 14, an inner peripheral hole 36a is formed on the radially inner side of the main plate 36, penetrating the main plate 36 in the fan axial direction Da.

[0054] The rotor coupling part 38 is a cylindrical rib centered on the fan axis CL, and protrudes from the main plate 36 to the other side in the fan axial direction Da. The motor rotor 161 is fitted and stored radially inside the rotor coupling part 38. In this way, the rotor coupling part 38 is fixed to the motor rotor 161. And, by fixing the rotor coupling part 38 to the motor rotor 161, the centrifugal fan 18 is fixed to the motor rotor 161.

[0055] Further, the main board 36 has a main board outer peripheral end portion 362. The main board outer peripheral end portion 362 is an end portion provided on the outer side in the fan diameter direction Dr of the main board 36. The main board outer peripheral end portion 362 and the side plate outer peripheral end portion 342 are arranged to be separated from each other in the fan axis direction Da. And, the main board outer peripheral end portion 362 and the side plate outer peripheral end portion 342 form an air outlet 18a through which the air passing through the inter-wing flow path 32a blows out between the main board outer peripheral end portion 362 and the side plate outer peripheral end portion 342. That is, the main board outer peripheral end portion 362 and the side plate outer peripheral end portion 342 constitute an air blowing portion of the centrifugal fan 18 where the air outlet 18a is formed. The air outlet 18a of the centrifugal fan 18 opens toward the outer side in the fan diameter direction Dr and is formed over the entire circumference of the centrifugal fan 18 centered on the fan axis CL.

[0056] In the present embodiment, the position of the main board outer peripheral end portion 362 in the fan diameter direction Dr is aligned with the position of the side plate outer peripheral end portion 342. That is, as shown in FIGS. 2 and 4, the outer diameter Dmo of the main board 36 and the outer diameter Dso of the side plate 34 are the same size, which is the outer diameter Dout of the centrifugal fan 18.

[0057] Also, the side plate inner and outer diameter ratio, which is the ratio of the inner diameter Dsi of the side plate 34 to the outer diameter Dso of the side plate 34, is calculated as Dsi / Dso. In the present embodiment, the Dsi / Dso is "0.5 < Dsi / Dso < 0.7". Specifically, in the present embodiment, the Dsi / Dso is "Dsi / Dso = 0.55". Note that the inner diameter Dsi of the side plate 34 is, in other words, also the diameter of the intake hole 34a formed in the side plate 34.

[0058] As shown in FIGS. 2 and 4, each of the plurality of blades 32 has a blade leading edge portion 323 provided on the inner side in the fan diameter direction Dr and a blade trailing edge portion 324 provided on the outer side in the fan diameter direction Dr. The blade leading edge portion 323 is an edge portion formed on the upstream side in the air flow direction of the air flowing through the intake hole 34a and into the inter-wing flow path 32a among the blades 32. Also, the blade trailing edge portion 324 is an edge portion formed on the downstream side in the air flow direction of the air flowing through the inter-wing flow path 32a among the blades 32.

[0059] The wing leading edge portion 323 is connected to the side plate 34 and the main plate 36, and extends from the side plate 34 side to the main plate 36 side. The wing trailing edge portion 324 is also connected to the side plate 34 and the main plate 36, and extends from the side plate 34 side to the main plate 36 side.

[0060] The blade leading edge portion 323 is formed so as to be located inward in the fan radial direction Dr toward the main plate 36. Specifically, the blade leading edge portion 323 includes a first leading edge portion 323a and a second leading edge portion 323b. The first leading edge portion 323a and the second leading edge portion 323b are formed so as to extend linearly, and the first leading edge portion 323a and the second leading edge portion 323b are connected in series. The first leading edge portion 323a is connected to the side plate 34. The second leading edge portion 323b is connected to the main plate 36 and is provided between the first leading edge portion 323a and the main plate 36.

[0061] The angle that the second leading edge portion 323b forms with the fan axis CL is smaller than the angle that the first leading edge portion 323a forms with the fan axis CL. More specifically, in the vertical cross sections of Figures 2 and 4, the first leading edge portion 323a extends linearly in a direction perpendicular to the fan axis CL. The second leading edge portion 323b extends linearly at an angle with respect to the fan axis CL so as to be positioned outward in the fan radial direction Dr toward one side of the fan axial direction Da.

[0062] Therefore, the one-side diameter Df1 of the second leading edge portion 323b is larger than the other-side diameter Df2 of the second leading edge portion 323b. The one-side diameter Df1 of the second leading edge portion 323b is a diameter centered on the fan axis CL at an end of the second leading edge portion 323b on one side in the fan axial direction Da. The other-side diameter Df2 of the second leading edge portion 323b is a diameter centered on the fan axis CL at an end of the second leading edge portion 323b on the other side in the fan axial direction Da.

[0063] The trailing edge portion 324 extends such that it is located more inward in the fan diameter direction Dr toward one side in the fan axis direction Da. Specifically, in the longitudinal sections of FIGS. 2 and 4, the trailing edge portion 324 is formed in a linear shape inclined with respect to the fan axis CL such that the side plate 34 side is located inward in the fan diameter direction Dr with respect to the main plate 36 side.

[0064] Therefore, the diameter Db1 on one side of the trailing edge portion 324 is smaller than the diameter Db2 on the other side of the trailing edge portion 324. The diameter Db1 on one side of the trailing edge portion 324 is the diameter centered on the fan axis CL that the trailing edge portion 324 has at one end in the fan axis direction Da. Also, the diameter Db2 on the other side of the trailing edge portion 324 is the diameter centered on the fan axis CL that the trailing edge portion 324 has at the other end in the fan axis direction Da.

[0065] As shown in FIGS. 2 and 4, the diameter Db2 on the other side of the trailing edge portion 324 is also the maximum outer diameter of the blade 32 centered on the fan axis CL. Between the diameter Db2 on the other side of the trailing edge portion 324 and the outer diameter Dmo of the main plate 36, the relationship of "Db2 < Dmo ≦ 1.13 × Db2" holds. Specifically, in this embodiment, the relationship between the diameter Db2 on the other side of the trailing edge portion 324 and the outer diameter Dmo of the main plate 36 is "Dmo = 1.06 × Db2".

[0066] Also, as shown in FIGS. 2 and 4, a part of the leading edge portion 323 is within the axial range Hb1 included in the entire width Hb that the trailing edge portion 324 occupies in the fan axis direction Da. A part of the leading edge portion 323 within the axial range Hb1 is, specifically, a part including the end on the main plate 36 side of the second leading edge portion 323b.

[0067] The axial height H2 that the portion Psi where the other surface 343 of the side plate starts to expand outward in the fan diameter direction Dr from the inner peripheral end portion 341 of the side plate has with respect to the main plate guide surface 36b along the fan axis direction Da and the outer diameter Dso of the side plate 34 are in the relationship of "0.06 < H2 / Dso < 0.20". Specifically, in this embodiment, H2 / Dso is "H2 / Dso = 0.082".

[0068] In the centrifugal fan 18 of this embodiment, the blade trailing edge portion 324 is connected to the side plate 34 on the inside in the fan radial direction Dr of the side plate outer peripheral end portion 342. At the same time, the blade trailing edge portion 324 is connected to the main plate 36 on the inside in the fan radial direction Dr of the main plate outer peripheral end portion 362. In other words, the side plate 34 and the main plate 36 each extend further outward in the fan radial direction Dr than the blade trailing edge portion 324. Specifically, the dimensional relationship between the outer diameter Dso of the side plate 34 and the one-side diameter Db1 of the blade trailing edge portion 324 is "Dso>Db1", and the dimensional relationship between the outer diameter Dmo of the main plate 36 and the other-side diameter Db2 of the blade trailing edge portion 324 is "Dmo>Db2".

[0069] As described above, the first case member 22 is disposed away from the side plate 34 of the centrifugal fan 18, and therefore the side plate 34 forms a case side plate gap 34b between the first case member 22 and the side plate 34. For example, this case side plate gap 34b is formed so as to be as narrow as possible within a range that prevents interference between the first case member 22 and the centrifugal fan 18.

[0070] The first case outer peripheral portion 222 extends from the first cover portion 221 and is provided so as to overlap the side plate outer peripheral end portion 342 on the outside in the fan radial direction Dr. The inner diameter Dc1 of the first case outer peripheral portion 222 is larger than the outer diameter Dso of the side plate 34. Therefore, the side plate outer peripheral end portion 342 faces the first case outer peripheral portion 222 in the fan radial direction Dr, and forms an opening end 34c of the case side plate gap 34b between the first case outer peripheral portion 222 and the side plate outer peripheral end portion 342. The opening end 34c of the case side plate gap 34b is located inside the air outlet 12a of the casing 12 in the fan radial direction Dr, and the case side plate gap 34b is connected to the fan outer peripheral flow path 12b at the opening end 34c.

[0071] In this embodiment, as shown in Figures 5 and 6, the thickness tb of the blade 32 is not constant at the blade trailing edge 324. Specifically, the thickness tb of the blade 32 increases toward the side plate 34 at the blade trailing edge 324. For example, the side plate-side trailing edge thickness tb1, which is the thickness tb of the blade 32 at the portion of the blade trailing edge 324 that connects to the side plate 34, is greater than the main plate-side trailing edge thickness tb2, which is the thickness tb of the blade 32 at the portion of the blade trailing edge 324 that connects to the main plate 36.

[0072] In this way, the thickness tb of the blade 32 at the blade trailing edge 324 changes depending on the axial position, and accordingly, the surface shape of the blade trailing edge 324 also changes depending on the axial position. Note that the air flow around the blade 32 is represented by a dashed line in Figure 6.

[0073] 6, the blade trailing edge portion 324 has a trailing edge outer surface 324a which is the surface of the blade trailing edge portion 324. The trailing edge outer surface 324a connects the pressure side and the suction side of the blade 32 at the blade trailing edge portion 324, and is convexly curved in a cross section perpendicular to the fan axis CL. Furthermore, in the cross section, the radius of curvature Rb of the trailing edge outer surface 324a becomes larger toward the side plate 34 side. For example, the side plate side radius of curvature Rb1 which is the radius of curvature Rb of the trailing edge outer surface 324a at the portion of the blade trailing edge portion 324 which is connected to the side plate 34 is larger than the main plate side radius of curvature Rb2 which is the radius of curvature Rb at the portion of the blade trailing edge portion 324 which is connected to the main plate 36.

[0074] 5, a blade trailing edge 91 of a centrifugal fan of a comparative example to be compared with this embodiment is indicated by a dashed line. In this centrifugal fan of the comparative example, the blade trailing edge 91 is parallel to the fan axis CL, and the thickness tb of the blade 32 at the blade trailing edge 91 is constant. Except for these points, the centrifugal fan of the comparative example is the same as the centrifugal fan 18 of this embodiment.

[0075] The centrifugal fan 18 configured as above rotates together with the motor rotor 161 in the fan rotation direction DRf as shown in Figs. 2 and 3. As a result, the blades 32 of the centrifugal fan 18 impart momentum to the air, so that the centrifugal fan 18 draws in air from the intake holes 34a as indicated by arrow FLa, and the drawn-in air flows radially outward through the inter-blade flow passages 32a as indicated by arrows FL1, FL2, and FL3. The centrifugal fan 18 then blows out the air that has passed through the inter-blade flow passages 32a radially outward from the outlet 18a as indicated by arrow FLb. The air blown out from the outlet 18a passes through the fan outer circumferential flow passage 12b of the casing 12 and is discharged to the outside of the blower 10 from the air outlet 12a.

[0076] As described above, according to this embodiment, as shown in Figures 2 and 4, in each of the multiple blades 32, the blade trailing edge portion 324 is formed so as to be positioned more inward in the fan radial direction Dr toward one side of the fan axial direction Da.

[0077] Here, the air flow in the inter-blade passage 32a formed between the blades 32 will be described. The air flow in the inter-blade passage 32a once separates from the side plate 34 as indicated by arrow FL1 on the upstream side of the inter-blade passage 32a, and generates a vortex WH on the other side 343 of the side plate. The air flow in the inter-blade passage 32a then once separates from the side plate 34 in this way, and then advances as indicated by arrow FL2. In other words, the air flow is biased to one side of the fan axial direction Da, so as to once separate from the side plate 34 and then reattach to the side plate 34.

[0078] In contrast, in the centrifugal fan 18 of the present embodiment, as described above, since the blade trailing edge portion 324 is formed so as to be located closer to the inner side in the fan diameter direction Dr toward one side in the fan axis direction Da, the amount of work on the main plate 36 side performed by each blade 32 becomes larger than that on the side plate 34 side. As a result, the air flow can be drawn again toward the main plate 36 side as indicated by the arrow FL3 near the outlet of the inter-blade flow path 32a. As a result, for example, compared with the case where the blade trailing edge portion 324 is parallel to the fan axis CL, the velocity distribution of the air flow near the outlet of the inter-blade flow path 32a can be made closer to a distribution without bias in the fan axis direction Da, and it is possible to reduce the noise of the centrifugal fan 18.

[0079] Further, in the centrifugal fan 18, Dsi / Dso, which is the ratio of the inner diameter Dsi of the side plate 34 to the outer diameter Dso of the side plate 34, is "0.5 < Dsi / Dso < 0.7". Therefore, for a centrifugal fan in which the air flow in the inter-blade flow path 32a biases toward the side plate 34 side near the outlet of the inter-blade flow path 32a if the blade trailing edge portion 324 is temporarily parallel to the fan axis CL, the above-described configuration in which the blade trailing edge portion 324 is located closer to the inner side in the fan diameter direction Dr toward one side in the fan axis direction Da can be used. Therefore, the above-described configuration of the blade trailing edge portion 324 of the present embodiment can be used so as to appropriately reduce the noise of the centrifugal fan 18.

[0080] In addition, when Dsi / Dso is, for example, 0.5 or less, the length of the inter-blade flow path 32a after the air flow is biased to one side in the fan axis direction Da as shown by the arrow FL2 is ensured to be sufficiently long. Therefore, even if the blade trailing edge 324 is parallel to the fan axis CL, the bias of the air flow to one side in the fan axis direction Da is alleviated before the air flow reaches the blade trailing edge 324 after being biased to one side in the fan axis direction Da. On the other hand, when Dsi / Dso is, for example, 0.7 or more, the air flow in the inter-blade flow path 32a reaches the blade trailing edge 324 before being biased to one side in the fan axis direction Da so as to reattach to the side plate 34. In short, the air flows indicated by the arrows FL1 and FL2 are interrupted midway. Therefore, in order to effectively utilize the above-described configuration in which the blade trailing edge 324 is located closer to the inside in the fan diameter direction Dr as it is closer to one side in the fan axis direction Da for noise reduction of the centrifugal fan 18, the relationship of "0.5 < Dsi / Dso < 0.7" is necessary.

[0081] The necessity of the relationship of "0.5 < Dsi / Dso < 0.7" has been confirmed, for example, by changing the magnitude of Dsi / Dso in a simulation by CFD and obtaining the analysis results. CFD is an abbreviation of "Computational Fluid Dynamics". In the centrifugal fan of this simulation example, the configuration of the blades 32 is the same as that of the above comparative example. That is, in the centrifugal fan of the simulation example, the blade trailing edge 91 (see FIG. 5) is parallel to the fan axis CL, and the thickness tb of the blade 32 at the blade trailing edge 91 is constant. Except for these points, the centrifugal fan of this simulation example is the same as the centrifugal fan 18 of the present embodiment.

[0082] The analysis results obtained from the CFD simulation are shown in Figures 7A to 7D. In this simulation, the rotation speed of the centrifugal fan is constant. In Figures 7A to 7D, arrows A1 and A2 indicate the direction of the air flow in the inter-blade passage 32a. Position P1 indicates the position where the side plate 34 faces the inter-blade passage 32a, and position P2 indicates the position where the main plate 36 faces the inter-blade passage 32a. In Figures 7A to 7D, the speed of the air flow (in other words, the flow velocity) in the inter-blade passage 32a is represented by differences in hatching.

[0083] Specifically, Fig. 7A shows the velocity distribution of the airflow in the inter-blade passage 32a obtained when Dsi / Dso = 0.72. According to Fig. 7A, when Dsi / Dso = 0.72, the high-speed portion of the airflow velocity distribution near the outlet of the inter-blade passage 32a (i.e., near the blade trailing edge 91 in Fig. 5) is biased toward the other side of the fan axial direction Da (i.e., toward the main plate 36).

[0084] 7B shows the airflow velocity distribution in the inter-blade passage 32a obtained when "Dsi / Dso=0.68", and Fig. 7C shows the airflow velocity distribution in the inter-blade passage 32a obtained when "Dsi / Dso=0.55". According to Fig. 7B and Fig. 7C, when "Dsi / Dso=0.68" and "Dsi / Dso=0.55", the high-speed portion of the airflow velocity distribution near the outlet of the inter-blade passage 32a is biased to one side of the fan axial direction Da (i.e., the side panel 34 side).

[0085] Moreover, Fig. 7D shows the velocity distribution of the airflow in the inter-blade passage 32a obtained when "Dsi / Dso = 0.48". According to Fig. 7D, when "Dsi / Dso = 0.48", the velocity distribution of the airflow near the outlet of the inter-blade passage 32a is not biased in the fan axial direction Da.

[0086] From the velocity distributions of the airflows shown in FIGS. 7A to 7D, the following can be said. That is, when "0.5 < Dsi / Dso < 0.7" as shown in FIGS. 7B and 7C, if the trailing edge portion 324 of the blade is inclined with respect to the fan axis direction Da as in the present embodiment, the velocity distribution of the airflow near the outlet of the inter-blade flow path 32a approaches a state where there is no bias in the fan axis direction Da. This is because the trailing edge portion 324 (see FIG. 2) inclined with respect to the fan axis direction Da as in the present embodiment acts to draw the airflow near the outlet of the inter-blade flow path 32a toward the main plate 36 side, as described above, compared to the trailing edge portion 91 parallel to the fan axis CL. Therefore, in this case, the inclination of the trailing edge portion 324 with respect to the fan axis direction Da as in the present embodiment leads to a reduction in the noise of the centrifugal fan 18.

[0087] On the other hand, in FIGS. 7A and 7D, the velocity distribution of the airflow near the outlet of the inter-blade flow path 32a is not such that the high-speed portion is biased toward the side plate 34 side. Therefore, when "0.7 ≦ Dsi / Dso" and when "Dsi / Dso ≦ 0.5", even if the airflow near the outlet of the inter-blade flow path 32a is drawn toward the main plate 36 side, the velocity distribution of the airflow near the outlet does not approach a state where there is no bias in the fan axis direction Da. That is, in this case, even if the trailing edge portion 324 is inclined with respect to the fan axis direction Da as in the present embodiment, this does not lead to a reduction in the noise of the centrifugal fan 18.

[0088] As described above, from the analysis results of FIGS. 7A to 7D, it can be said that in order to effectively utilize the configuration in which the trailing edge portion 324 is inclined with respect to the fan axis direction Da as in the present embodiment for reducing the noise of the centrifugal fan 18, the relationship of "0.5 < Dsi / Dso < 0.7" is required.

[0089] Furthermore, when comparing the centrifugal fan 18 of this embodiment with the centrifugal fan of the comparative example in which the blade trailing edge portion 91 (see FIG. 5) is parallel to the fan axis CL, the noise reduction of the centrifugal fan 18 is achieved in most frequency ranges, as shown in FIG. 8. In FIG. 8, the solid line S1 indicates the SPL of this embodiment, and the dashed line S2 indicates the SPL of the comparative example. SPL is an abbreviation for "Sound Pressure Level."

[0090] Furthermore, as shown in Fig. 9, in this embodiment, the noise of the centrifugal fan 18 was reduced by 2 dB in overall value compared to the comparative example. "OA" on the vertical axis in Fig. 9 is an abbreviation for overall value.

[0091] (1) Furthermore, according to this embodiment, the side plate other surface 343 is located on the other side of the fan axial direction Da as it moves outward in the fan radial direction Dr. In the vertical cross sections of Fig. 2 and Fig. 4, the radius of curvature of the side plate other surface 343 increases as it moves outward in the fan radial direction Dr. Therefore, while obtaining the noise reduction effect due to the configuration in which the blade trailing edge portion 324 is located more inward in the fan radial direction Dr as it moves to one side in the fan axial direction Da, it is possible to guide the air sucked into the centrifugal fan 18 from one side in the fan axial direction Da to flow outward in the fan radial direction Dr.

[0092] (2) According to this embodiment, as shown in Fig. 2 and Fig. 4, the blade leading edge 323 of each of the blades 32 extends from the side plate 34 side to the main plate 36 side, and is formed to be located more inward in the fan radial direction Dr as it approaches the main plate 36 side. Therefore, the length of the blade 32 is longer on the main plate 36 side than on the side plate 34 side, so that the amount of work performed by each blade 32 on the main plate 36 side can be made larger than that on the side plate 34 side. This also makes it possible to correct the bias of the air flow in the inter-blade flow passage 32a toward one side of the fan axial direction Da.

[0093] (3) Further, according to the present embodiment, the side plate 34 and the main plate 36 each extend to the outside of the fan diameter direction Dr with respect to the trailing edge portion 324 of the blade. Therefore, the trailing edge portion 324 of the blade where the flow velocity of the air flow is maximum can be separated from the opening end 34c of the case side plate gap 34b. This advantageously acts in reducing the noise of the centrifugal fan 18.

[0094] Also, since the side plate 34 and the main plate 36 each extend to the outside of the fan diameter direction Dr with respect to the trailing edge portion 324 of the blade, the rapid expansion of the air flow in the fan axis direction Da immediately after the air flow exits from the inter-blade flow path 32a is suppressed. Thereby, the loss caused by the rapid expansion of the air flow can be suppressed, and it can contribute to the reduction of the noise of the centrifugal fan 18.

[0095] For example, the relationship between the ratio Dmo / Db2 of the outer diameter Dmo of the main plate 36 to the other-side diameter Db2 of the trailing edge portion 324 of the blade and the noise reduction effect is as shown in FIG. 10. That is, the greater the Dmo / Db2, the higher the noise reduction effect. As can be seen from FIG. 10, the fact that the side plate 34 and the main plate 36 extend to the outside of the fan diameter direction Dr with respect to the trailing edge portion 324 of the blade acts to enhance the noise reduction effect. In the experiment of FIG. 10, the outer diameter Dso of the side plate 34 is the same as the outer diameter Dmo of the main plate 36.

[0096] (4) Further, according to the present embodiment, between the other-side diameter Db2 of the trailing edge portion 324 of the blade and the outer diameter Dmo of the main plate 36, the relationship of "Db2 < Dmo ≦ 1.13×Db2" holds. And according to FIG. 10, when Dmo / Db2 exceeds 1.13, although the noise reduction effect gradually increases as Dmo / Db2 increases, it does not change much with respect to Dmo / Db2. Therefore, it is possible to obtain a noise reduction effect while avoiding the physical size of the centrifugal fan 18 from becoming larger than necessary.

[0097] (5) Furthermore, according to this embodiment, the first case outer circumferential portion 222 of the first case member 22 is provided to overlap the outside of the side plate outer circumferential end portion 342 of the centrifugal fan 18 in the fan radial direction Dr. The side plate outer circumferential end portion 342 faces the first case outer circumferential portion 222 in the fan radial direction Dr, and forms the opening end 34c of the case side plate gap 34b between itself and the first case outer circumferential portion 222.

[0098] Therefore, the opening end 34c of the case side panel gap 34b is located inside the air outlet 12a of the casing 12 in the fan radial direction Dr, so that the air pressure at the opening end 34c is lower than the air pressure at the air outlet 12a. This makes it possible to suppress the backflow of the blown air flowing from the opening end 34c into the case side panel gap 34b, compared to when the opening end 34c is open outside the air outlet 12a, for example.

[0099] (6) Furthermore, according to this embodiment, as shown in Figures 4 to 6, the blade trailing edge 324 extends from the side plate 34 side to the main plate 36 side, and the thickness tb of the blade 32 is larger at the blade trailing edge 324 toward the side plate 34 side. Therefore, the stall region ST of the airflow adjacent to the blade trailing edge 324 is larger on the side plate 34 side than on the main plate 36 side, and the airflow loss due to this stall region ST is larger on the side plate 34 side. This also acts to suppress the airflow around the blade trailing edge 324 from being biased to one side in the fan axial direction Da.

[0100] (7) Furthermore, according to this embodiment, as shown in Figs. 5 and 6, in a cross section perpendicular to the fan axis CL (for example, the cross section in Fig. 6), the trailing edge outer surface 324a of the blade trailing edge 324 is convexly curved, and the radius of curvature Rb of the trailing edge outer surface 324a becomes larger toward the side plate 34 side. Therefore, the pressure surface and the suction surface of the blade 32 can be smoothly connected at the blade trailing edge 324. Therefore, while maintaining the tendency that the air flow resistance around the blade trailing edge 324 is larger on the side plate 34 side than on the main plate 36 side, the overall flow resistance can be reduced compared to a case where the pressure surface and the suction surface are not smoothly connected at the blade trailing edge 324.

[0101] Second embodiment Next, a second embodiment will be described. In this embodiment, differences from the first embodiment will be mainly described. Also, parts that are the same as or equivalent to the above-mentioned embodiment will be omitted or simplified. This also applies to the following embodiments.

[0102] 11, in the present embodiment, similarly to the first embodiment, the blade trailing edge portion 324 is formed to be located more inward in the fan radial direction Dr toward one side in the fan axial direction Da. However, in the present embodiment, the shape of the blade trailing edge portion 324 is different from that in the first embodiment.

[0103] Specifically, the blade trailing edge portion 324 of this embodiment is formed to have one step shape, and is positioned stepwise inward in the fan radial direction Dr towards one side in the fan axial direction Da.

[0104] Except for the points described above, this embodiment is similar to the first embodiment. In this embodiment, the same effects as those of the first embodiment can be obtained from the configuration common to the first embodiment.

[0105] Third embodiment Next, a third embodiment will be described. In this embodiment, differences from the first embodiment will be mainly described.

[0106] 12, in the present embodiment, similarly to the first embodiment, the blade trailing edge portion 324 is formed to be located more inward in the fan radial direction Dr toward one side in the fan axial direction Da. However, in the present embodiment, the shape of the blade trailing edge portion 324 is different from that in the first embodiment.

[0107] Specifically, the blade trailing edge portion 324 of this embodiment is formed to have a plurality of steps, which are positioned stepwise inward in the fan radial direction Dr toward one side in the fan axial direction Da.

[0108] Except for the points described above, this embodiment is similar to the first embodiment. In this embodiment, the same effects as those of the first embodiment can be obtained from the configuration common to the first embodiment.

[0109] (Fourth embodiment) Next, a fourth embodiment will be described. In this embodiment, differences from the first embodiment will be mainly described.

[0110] 13, in the present embodiment, similarly to the first embodiment, the blade trailing edge portion 324 is formed to be positioned more inward in the fan radial direction Dr toward one side in the fan axial direction Da. However, in the present embodiment, the shape of the blade trailing edge portion 324 is different from that in the first embodiment.

[0111] Specifically, the blade trailing edge 324 of this embodiment extends parallel to the fan axis CL at a portion on one side in the fan axial direction Da including a portion of the blade trailing edge 324 that is connected to the side plate 34. Then, at a portion on the other side in the fan axial direction Da including a portion of the blade trailing edge 324 that is connected to the main plate 36, the blade trailing edge 324 is inclined with respect to the fan axis CL so as to be positioned more outward in the fan radial direction Dr toward the other side in the fan axial direction Da.

[0112] Except for the points described above, this embodiment is similar to the first embodiment. In this embodiment, the same effects as those of the first embodiment can be obtained from the configuration common to the first embodiment.

[0113] Fifth embodiment Next, a fifth embodiment will be described. In this embodiment, differences from the first embodiment will be mainly described.

[0114] 14, in the present embodiment, similarly to the first embodiment, the blade trailing edge 324 is formed to be positioned more inward in the fan radial direction Dr toward one side in the fan axial direction Da. However, in the present embodiment, the shape of the blade trailing edge 324 is different from that in the first embodiment.

[0115] Specifically, the wing trailing edge 324 in this embodiment extends in a curved manner.

[0116] Except for the points described above, this embodiment is similar to the first embodiment. In this embodiment, the same effects as those of the first embodiment can be obtained from the configuration common to the first embodiment.

[0117] Sixth embodiment Next, a sixth embodiment will be described. In this embodiment, differences from the first embodiment will be mainly described.

[0118] 15, in the present embodiment, similarly to the first embodiment, the side plate other surface 343 of the centrifugal fan 18 faces the other side of the fan axial direction Da and expands in the fan radial direction Dr, and is positioned on the other side of the fan axial direction Da toward the outside in the fan radial direction Dr. However, in the present embodiment, the shape of the side plate other surface 343 is different from that in the first embodiment.

[0119] Specifically, in the vertical cross section of blower 10 shown in Fig. 15, side panel other surface 343 has inner arc shape 343a and outer straight line shape 343d. Outer straight line shape 343d replaces outer arc shape 343b and outer straight line shape 343c (see Fig. 2) in the first embodiment.

[0120] In the vertical cross section of Fig. 15, the inner arc shape 343a and the outer straight line shape 343d of this embodiment are smoothly connected in the order of the inner arc shape 343a and the outer straight line shape 343d from the inside in the fan radial direction Dr. Also, the outer straight line shape 343d is a straight line inclined with respect to the fan axis CL so as to be located on the other side of the fan axial direction Da as it moves outward in the fan radial direction Dr. Thus, in the vertical cross section of Fig. 15, the side panel other surface 343 of this embodiment is formed by one arc and one straight line.

[0121] Except for the points described above, this embodiment is similar to the first embodiment. In this embodiment, the same effects as those of the first embodiment can be obtained from the configuration common to the first embodiment.

[0122] It should be noted that although this embodiment is a modification based on the first embodiment, this embodiment can also be combined with any of the second to fifth embodiments described above.

[0123] Seventh embodiment Next, a seventh embodiment will be described. In this embodiment, differences from the first embodiment will be mainly described.

[0124] 16, in the present embodiment, similarly to the first embodiment, the side plate other surface 343 of the centrifugal fan 18 faces the other side of the fan axial direction Da and expands in the fan radial direction Dr, and is positioned on the other side of the fan axial direction Da toward the outside in the fan radial direction Dr. However, in the present embodiment, the shape of the side plate other surface 343 is different from that of the first embodiment.

[0125] Specifically, in the vertical cross section of blower 10 shown in Fig. 16, side plate other surface 343 is formed as a single straight line inclined with respect to fan axis CL so as to be positioned on the other side of fan axial direction Da as it moves outward in fan radial direction Dr. Thus, in the vertical cross section of Fig. 16, side plate other surface 343 of this embodiment is formed as a single straight line.

[0126] (1) Therefore, while obtaining the noise reduction effect achieved by the configuration in which the blade trailing edge portion 324 is located further inward in the fan radial direction Dr toward one side of the fan axial direction Da, it is possible to guide the air sucked into the centrifugal fan 18 from one side of the fan axial direction Da to flow outward in the fan radial direction Dr.

[0127] Except for the points described above, this embodiment is similar to the first embodiment. In this embodiment, the same effects as those of the first embodiment can be obtained from the configuration common to the first embodiment.

[0128] It should be noted that although this embodiment is a modification based on the first embodiment, this embodiment can also be combined with any of the second to fifth embodiments described above.

[0129] Eighth embodiment Next, an eighth embodiment will be described. In this embodiment, differences from the first embodiment will be mainly described.

[0130] 17, in the present embodiment, similarly to the first embodiment, the side plate other surface 343 of the centrifugal fan 18 faces the other side of the fan axial direction Da and expands in the fan radial direction Dr, and is positioned on the other side of the fan axial direction Da toward the outside. However, in the present embodiment, the shape of the side plate other surface 343 is different from that of the first embodiment.

[0131] Specifically, in the vertical cross section of blower 10 shown in Fig. 17, side plate other surface 343 is formed in a single arc shape extending toward the other side in fan axial direction Da as it moves outward in fan radial direction Dr. Thus, in the vertical cross section of Fig. 17, side plate other surface 343 of this embodiment is formed in a single arc shape.

[0132] Except for the points described above, this embodiment is similar to the first embodiment. In this embodiment, the same effects as those of the first embodiment can be obtained from the configuration common to the first embodiment.

[0133] It should be noted that although this embodiment is a modification based on the first embodiment, this embodiment can also be combined with any of the second to fifth embodiments described above.

[0134] Ninth embodiment Next, a ninth embodiment will be described. In this embodiment, differences from the first embodiment will be mainly described.

[0135] 18, in the present embodiment, similarly to the first embodiment, the blade leading edge portion 323 extends from the side plate 34 side to the main plate 36 side, and is formed so as to be positioned more inward in the fan radial direction Dr as it approaches the main plate 36. However, in the present embodiment, the shape of the blade leading edge portion 323 is different from that in the first embodiment.

[0136] Specifically, the blade leading edge portion 323 of this embodiment has a third leading edge portion 323c in addition to the first leading edge portion 323a and the second leading edge portion 323b. The first leading edge portion 323a, the second leading edge portion 323b, and the third leading edge portion 323c are connected in series in this order from the side plate 34 side.

[0137] The third front edge portion 323c is connected to the main plate 36, and is provided between the second front edge portion 323b and the main plate 36. Moreover, the third front edge portion 323c is formed parallel to the fan axis CL in the vertical cross section of FIG.

[0138] Except for the points described above, this embodiment is similar to the first embodiment. In this embodiment, the same effects as those of the first embodiment can be obtained from the configuration common to the first embodiment.

[0139] It should be noted that although this embodiment is a modification based on the first embodiment, this embodiment can also be combined with any of the second to eighth embodiments described above.

[0140] Tenth embodiment Next, a tenth embodiment will be described. In this embodiment, differences from the first embodiment will be mainly described.

[0141] As shown in Fig. 19, the electric motor 16 of the present embodiment has a motor rotor 40 instead of the motor rotor 161 (see Fig. 2) of the first embodiment. Moreover, the centrifugal fan 18 of the present embodiment has a main plate outer circumferential portion 43 instead of the main plate 36 of the first embodiment, and has a rotor coupling portion 44 instead of the rotor coupling portion 38 of the first embodiment. In the present embodiment, the multiple blades 32, the side plate 34, the main plate outer circumferential portion 43, and the rotor coupling portion 44 are integrally configured.

[0142] Specifically, the motor rotor 40 of this embodiment is formed with an inner circumferential hole 40a corresponding to the inner circumferential hole 36a of the first embodiment, and the rotating shaft 14 is fitted into the inner circumferential hole 40a. As a result, the motor rotor 40 is directly fixed to the rotating shaft 14 and rotates integrally with the rotating shaft 14 about the fan axis CL.

[0143] The motor rotor 40 has a main plate inner peripheral portion 401 and a cylindrical portion 402. The main plate inner peripheral portion 401 has a disk-like shape that spreads in the fan radial direction Dr with the fan axis CL as the center. The main plate inner peripheral portion 401 has an inner peripheral main plate surface 401a. This inner peripheral main plate surface 401a is a curved surface that faces one side of the fan axial direction Da and spreads in the fan radial direction Dr, and is formed so as to be located on the other side of the fan axial direction Da as it moves outward in the fan radial direction Dr. The main plate inner peripheral portion 401 is a part of the motor rotor 40, but also has a function of guiding the air sucked in by the centrifugal fan 18, and is therefore also a part of the centrifugal fan 18.

[0144] 19, a gap is shown between the blades 32 and the inner peripheral portion 401 of the main plate of the motor rotor 40 for ease of illustration. Each blade 32 may be in contact with the inner peripheral portion 401 of the main plate, or may be separated from the inner peripheral portion 401 of the main plate with a gap therebetween as shown.

[0145] The tubular portion 402 of the motor rotor 40 has a cylindrical shape centered on the fan axis CL, and extends from the radially outer end of the main plate inner circumferential portion 401 to the other side in the fan axial direction Da. The rotor magnet 162 is fixed to the inside of this tubular portion 402.

[0146] The main plate outer peripheral portion 43 is disposed outward in the fan radial direction Dr relative to the main plate inner peripheral portion 401, and has a disk-like shape that spreads outward in the fan radial direction Dr with the fan axis CL as the center. In detail, the main plate outer peripheral portion 43 has a shape that continues from the main plate inner peripheral portion 401 and spreads outward in the fan radial direction Dr. Therefore, the main plate outer peripheral portion 43 and the main plate inner peripheral portion 401 as a whole correspond to the main plate 36 (see FIG. 2) of the first embodiment.

[0147] The main plate outer periphery 43 has an outer periphery main plate surface 43a facing one side in the fan axial direction Da. This outer periphery main plate surface 43a continues from the inner periphery main plate surface 401a and spreads outward in the fan radial direction Dr. The other blade ends 322 of the multiple blades 32 are respectively connected to the outer periphery main plate surface 43a. The outer periphery main plate surface 43a and the inner periphery main plate surface 401a collectively form a main plate guide surface 36b that guides the airflow inside the centrifugal fan 18.

[0148] Moreover, the main plate outer peripheral portion 43 has an outer peripheral end portion 431 which is an end portion provided on the outside in the fan radial direction Dr. This outer peripheral end portion 431 corresponds to the main plate outer peripheral end portion 362 (see FIG. 2) of the first embodiment.

[0149] The rotor coupling part 44 has a cylindrical shape centered on the fan axis CL, and extends from the radially inner end of the main plate outer circumferential part 43 to the other side in the fan axial direction Da. The cylindrical part 402 of the motor rotor 40 is fitted into the radially inner side of the rotor coupling part 44. In this way, the rotor coupling part 44 is fixed to the motor rotor 40. Then, by fixing the rotor coupling part 44 to the motor rotor 40, the centrifugal fan 18 is fixed to the motor rotor 40 and rotates integrally with the motor rotor 40.

[0150] Except for the points described above, this embodiment is similar to the first embodiment. In this embodiment, the same effects as those of the first embodiment can be obtained from the configuration common to the first embodiment.

[0151] Although this embodiment is a modification based on the first embodiment, it is also possible to combine this embodiment with any of the second to ninth embodiments described above.

[0152] (Other embodiments) (1) In each of the above-described embodiments, the centrifugal fan 18 is a turbofan as shown in FIG. 2. However, it may be another type of centrifugal fan, such as a radial fan.

[0153] (2) In each of the above-described embodiments, the electric motor 16 is an outer rotor type brushless DC motor as shown in Fig. 2, but the type of the motor is not limited. For example, the electric motor 16 may be an inner rotor type motor or a brushed motor.

[0154] (3) In each of the above-described embodiments, the second front edge portion 323b extends linearly in the vertical cross sections of FIGS. 2 and 4, but it may also be curved.

[0155] (4) In the first embodiment described above, the outer diameter Dmo of the main plate 36 and the outer diameter Dso of the side plate 34 are the same size as each other, but this is just an example. For example, the outer diameter Dmo of the main plate 36 may be larger than the outer diameter Dso of the side plate 34, or may be smaller than the outer diameter Dso of the side plate 34.

[0156] (5) The present invention is not limited to the above-described embodiment, and can be practiced in various modified forms. Furthermore, the above-described embodiments are not unrelated to each other, and can be appropriately combined, except in cases where the combination is clearly impossible.

[0157] In each of the above embodiments, the elements constituting the embodiment are not necessarily essential, unless otherwise specified as essential or considered to be obviously essential in principle. In each of the above embodiments, when the numbers, values, amounts, ranges, etc. of the components of the embodiment are mentioned, they are not limited to the specific numbers, except when specified as essential or when they are obviously limited to a specific number in principle. In each of the above embodiments, when the materials, shapes, positional relationships, etc. of the components are mentioned, they are not limited to the materials, shapes, positional relationships, etc., except when specified as essential or when they are obviously limited to a specific material, shape, positional relationship, etc. in principle.

[0158] (Features of the present invention) [Claim 1] A centrifugal fan that rotates around a fan axis (CL) to draw in air from one side in an axial direction (Da) of the fan axis and blows the drawn air outward in a radial direction (Dr) of the fan axis, a plurality of blades (32) arranged side by side around the fan axis and having a blade trailing edge portion (324) on the outer side in the radial direction; a side plate (34) formed with an intake hole (34a) through which air is drawn, the side plate (34) being provided on the one side in the axial direction of the plurality of blades and connected to each of the plurality of blades; a main plate (36, 43, 401) connected to each of the plurality of blades on the side opposite to the side plate side and extending in the radial direction; If the inner diameter of the side plate is Dsi and the outer diameter of the side plate is Dso, Dsi / Dso is 0.5 <Dsi / Dso<0.7であり、 a blade trailing edge portion formed so as to be positioned further inward in the radial direction toward the one side in the axial direction; [Claim 2] The side plate has a side plate other surface (343) that faces the other side opposite to the one side in the axial direction and expands in the radial direction, the other surface of the side plate is located toward the other side in the axial direction as it becomes more outward in the radial direction, The centrifugal fan according to claim 1, wherein in a longitudinal section including the fan axis, the radius of curvature of the other surface of the side plate increases toward the outer side in the radial direction. [Claim 3] The side plate has another surface (343) of the side plate that faces the other side opposite to the one side in the axial direction and extends in the radial direction. The other surface of the side plate is located on the other side in the axial direction toward the outer side in the radial direction. The centrifugal fan according to claim 1, wherein in a longitudinal section including the fan axis, the other surface of the side plate is formed by one arc or a straight line. [Claim 4] Each of the plurality of blades has a blade front edge portion (323) on the inner side in the radial direction. The centrifugal fan according to any one of claims 1 to 3, wherein the blade front edge portion extends from the side plate side to the main plate side and is formed so as to be located more on the inner side in the radial direction toward the main plate side. [Claim 5] The centrifugal fan according to claim 4, wherein a part of the blade front edge portion is within an axial range (Hb1) included in the entire width (Hb) occupied by the blade rear edge portion in the axial direction. [Claim 6] The centrifugal fan according to any one of claims 1 to 5, wherein the side plate and the main plate each extend to the outer side in the radial direction beyond the blade rear edge portion. [Claim 7] The side plate and the main plate each extend to the outer side in the radial direction beyond the blade rear edge portion. The centrifugal fan according to any one of claims 1 to 5, wherein when the maximum outer diameter of the plurality of blades is Db2 and the outer diameter of the main plate is Dmo, the relationship Db2 < Dmo ≦ 1.13 × Db2 holds. [Claim 8] A centrifugal fan constituting a part of a blower (10), The blower has a side plate adjacent case (22) provided on the side opposite to the blade side with respect to the side plate and arranged away from the side plate. The side plate has an outer peripheral end portion (342) provided on the outside in the radial direction, and forms a case side plate gap (34b) between the side plate and the side plate adjacent case, The side plate adjacent case has a case outer periphery (222) provided so as to overlap the outer periphery end of the side plate on the outside in the radial direction, 8. The centrifugal fan according to claim 1, wherein an outer peripheral end portion of the side plate faces the outer peripheral portion of the case in the radial direction and forms an opening end (34c) of the case side plate gap between the outer peripheral portion of the case and the outer peripheral portion of the case. [Claim 9] The wing trailing edge portion extends from the side plate side to the main plate side, 9. The centrifugal fan according to claim 1, wherein a thickness (tb) of each of the plurality of blades increases toward the side plate at the blade trailing edge portion. [Claim 10] 10. The centrifugal fan according to claim 9, wherein, in a cross section perpendicular to the fan axis, the blade trailing edge has a convexly curved trailing edge outer surface (324a), and a radius of curvature (Rb) of the trailing edge outer surface increases toward the side plate. [Explanation of symbols]

[0159] 18 Centrifugal Fan 32 Wings 324 Wing trailing edge 34 Side Panel 34a Air intake 36 Main plate Da Fan shaft direction (axial direction of the fan shaft) Dr Fan radial direction (radial direction of the fan shaft center) Dsi Side plate inner diameter Dso Outer diameter of side plate

Claims

1. A centrifugal fan that rotates about a fan axis (CL) to draw in air from one side in an axial direction (Da) of the fan axis and blows the drawn air outward in a radial direction (Dr) of the fan axis, A plurality of blades (32) arranged side by side around the fan axis and having a blade trailing edge portion (324) on the outer side in the radial direction; a side plate (34) formed with an intake hole (34a) through which air is drawn, the side plate (34) being provided on the one side in the axial direction of the plurality of blades and connected to each of the plurality of blades; a main plate (36, 43, 401) connected to each of the plurality of blades on the side opposite to the side plate side and extending in the radial direction; When the inner diameter of the side plate is Dsi and the outer diameter of the side plate is Dso, Dsi / Dso is 0.5<Dsi / Dso<0.7, a blade trailing edge portion formed so as to be positioned further inward in the radial direction toward the one side in the axial direction;

2. The side plate has a side plate other surface (343) that faces the other side opposite to the one side in the axial direction and expands in the radial direction, the other surface of the side plate is located toward the other side in the axial direction as it becomes more outward in the radial direction, 2. The centrifugal fan according to claim 1, wherein in a vertical cross section including the fan axis, a radius of curvature of the other surface of the side plate increases toward the outside in the radial direction.

3. The side plate has a side plate other surface (343) that faces the other side opposite to the one side in the axial direction and expands in the radial direction, the other surface of the side plate is located toward the other side in the axial direction as it becomes more outward in the radial direction, 2. The centrifugal fan according to claim 1, wherein in a vertical cross section including the fan axis, the other surface of the side plate is formed by a single circular arc or straight line.

4. Each of the plurality of blades has a blade leading edge portion (323) on the inner side in the radial direction, 4. The centrifugal fan according to claim 1, wherein the blade leading edge portion extends from the side plate toward the main plate and is formed so as to be located radially inward as it approaches the main plate.

5. The centrifugal fan according to claim 4 , wherein a portion of the blade leading edge is within an axial range (Hb1) included in a total width (Hb) occupied by the blade trailing edge in the axial direction.

6. 4. The centrifugal fan according to claim 1, wherein the side plate and the main plate each extend radially outward beyond the blade trailing edge.

7. the side plate and the main plate each extend radially outward beyond the trailing edge of the wing, 4. The centrifugal fan according to claim 1, wherein when a maximum outer diameter of the plurality of blades is Db2 and an outer diameter of the main plate is Dmo, a relationship of Db2<Dmo≦1.13×Db2 is satisfied.

8. A centrifugal fan constituting a part of a blower (10), The blower has a side plate adjacent case (22) provided on the side plate opposite to the blade side and spaced apart from the side plate, The side plate has an outer peripheral end portion (342) provided on the outside in the radial direction, and forms a case side plate gap (34b) between the side plate and the adjacent case, The side plate adjacent case has a case outer periphery (222) provided so as to overlap the outer periphery end of the side plate on the outside in the radial direction, 4. The centrifugal fan according to claim 1, wherein an outer peripheral end portion of the side plate faces the outer peripheral portion of the case in the radial direction, and forms an opening end (34c) of the case side plate gap between the outer peripheral portion of the case and the outer peripheral portion of the case.

9. The wing trailing edge portion extends from the side plate side to the main plate side, 4. The centrifugal fan according to claim 1, wherein a thickness (tb) of each of the plurality of blades is increased toward the side plate at the trailing edge of the blade.

10. 10. The centrifugal fan according to claim 9, wherein, in a cross section perpendicular to the fan axis, the blade trailing edge portion has a convexly curved trailing edge outer surface (324a), and a radius of curvature (Rb) of the trailing edge outer surface becomes larger toward the side plate.

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