CN117597521A

CN117597521A - Centrifugal fan

Info

Publication number: CN117597521A
Application number: CN202280047009.0A
Authority: CN
Inventors: 石井文也; 山冈润
Original assignee: Denso Corp
Current assignee: Denso Corp
Priority date: 2021-09-02
Filing date: 2022-08-23
Publication date: 2024-02-23

Abstract

The centrifugal fan sucks air from one side in the axial direction (Da) of the fan shaft center by rotating around the fan shaft Center (CL) and blows the sucked air out of the radial direction (Dr) of the fan shaft center. The centrifugal fan is provided with a plurality of blades (32), side plates (34), and main plates (36, 43, 401). The blades are arranged around the fan axis and have blade trailing edge portions (324) on the radially outer side. An air intake hole (34 a) for sucking air is formed in a side plate, and the side plate is provided on one side in the axial direction with respect to the plurality of blades and is connected to each of the plurality of blades. The main plate is coupled to each of the plurality of blades on the side opposite to the side plate side, and expands 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, and the blade trailing edge portion is formed so as to be located radially inward as it is located closer to the axial direction.

Description

Centrifugal fan

Cross-reference to related applications

The present application is based on Japanese patent application Nos. 2021-143526 of the application of month 2 of year 2021 and 2022 of month 26 of year 2022, and the contents of the descriptions thereof are incorporated herein by reference.

Technical Field

The present invention relates to a centrifugal fan that rotates to cause air to flow.

Background

The centrifugal fan described in patent document 1 has a plurality of blades (i.e., vanes) having a three-dimensional shape, a main plate, and side plates. One end face of each blade in the span direction is fixed to the main plate, and the other end face of each blade in the span direction is fixed to the side plate.

In addition, in the three-dimensional blade, the main flow of the intake air flow is blown out toward the main plate side not along the side plate, and therefore, the intake air flow generates a biased velocity distribution and noise, which is shown as a technical problem in patent document 1.

In contrast, in the centrifugal fan of patent document 1, each blade is formed such that the diameter of the blade trailing edge portion of the blade increases on the main plate side than on the side plate side. Thus, patent document 1 describes that the distribution of the main flow velocity between the blades is improved, and noise is improved.

Prior art literature

Patent literature

Patent document 1: international publication No. 2009/139422

In general, as a centrifugal fan, it is assumed that the ratio of the inside diameter of a side plate (i.e., the diameter of an intake hole of the centrifugal fan) to the outside diameter of the side plate (i.e., the outside diameter of the side plate) is different from the inside diameter of the fan. However, patent document 1 does not mention the inside-outside diameter ratio of the fan.

Further, since the smaller the inside-outside diameter ratio of the fan, the longer the air flow paths (in other words, the inter-blade flow paths) formed between the blades are, in the centrifugal fan in which the inside-outside diameter ratio of the fan is smaller than a certain level, an air flow not described in patent literature 1 is generated in the inter-blade flow paths.

Specifically, the air flow in the inter-vane flow path is peeled off from the back surface of the side plate (i.e., the surface of the side plate on the vane side) near the suction hole, is temporarily deflected to the main plate side, and then flows so as to adhere to the side plate again in the middle of the inter-vane flow path. Therefore, at the outlet of the inter-vane flow path, the air flow flows toward the side plate side, and a velocity distribution of the air flow toward the one side is generated in the axial direction of the fan. Noise is generated due to the velocity distribution of the deflected air flow in the vicinity of the outlet of the inter-vane flow path. The inventors have found such a new finding.

Disclosure of Invention

In view of the above, an object of the present invention is to provide a centrifugal fan capable of suppressing generation of noise caused by a speed distribution of a biased air flow in the vicinity of an outlet of an inter-vane flow path.

In order to achieve the above object, according to one aspect of the present invention, a centrifugal fan that sucks air from one side in an axial direction of a fan shaft center by rotating around the fan shaft center and blows the sucked air radially outward of the fan shaft center includes:

A plurality of blades arranged around the fan axis and having blade trailing edge portions on the outer side in the radial direction;

a side plate that forms an intake hole through which air is sucked, is provided on one side in the axial direction with respect to the plurality of blades, and is connected to each of the plurality of blades; and

a main plate connected to each of the plurality of blades on a side opposite to the side plate side, the main plate expanding in a radial direction,

in the case where the inner diameter of the side plate is set to Dsi and the outer diameter of the side plate is set to Dso, dsi/Dso is 0.5 < Dsi/Dso < 0.7,

the blade trailing edge portion is formed so as to be located radially inward as it is closer to one side in the axial direction.

Here, in the inter-vane flow path, which is the air flow path formed between the vanes, the air flow is offset to one side in the axial direction so as to be temporarily peeled off from the side plate and then reattached to the side plate. In contrast, in the centrifugal fan described above, since the trailing edge portion of the blade is formed so as to be located radially inward as it is located closer to the axial direction, the amount of work done on the main plate side by each blade is increased as compared with the side plate side, and the air flow can be sucked again to the main plate side in the vicinity of the outlet of the inter-blade flow path. As a result, for example, compared with a case where the blade trailing edge portion is parallel to the fan axis, the speed distribution of the air flow can be made closer to the distribution which is not biased in the axial direction in the vicinity of the outlet of the inter-blade flow path, and the centrifugal fan can be reduced in noise.

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 is 0.5 < Dsi/Dso < 0.7. Therefore, in the centrifugal fan in which the air flow in the inter-blade flow path is biased toward the side plate side in the vicinity of the outlet of the inter-blade flow path, assuming that the blade trailing edge portion is parallel to the fan axis, the above-described structure can be used in which the side of the blade trailing edge portion closer to the axial direction is located radially inward. Therefore, in order to properly reduce noise of the centrifugal fan, the trailing edge portion of the blade can be used.

The bracketed reference symbols for the respective components and the like indicate examples of correspondence between the components and the like and specific components and the like described in the embodiments described below.

Drawings

Fig. 1 is a perspective view showing an appearance of a blower according to a first embodiment.

Fig. 2 is a longitudinal sectional view of the blower in a plane including the fan axis in the first embodiment, that is, a sectional view schematically showing a section II-II of fig. 1.

Fig. 3 is a plan view showing a centrifugal fan and a rotation shaft of the blower in the first embodiment in a direction from one side to the other side in the axial direction of the fan.

Fig. 4 is a cross-sectional view showing the same cross-section as fig. 2.

Fig. 5 is a perspective view illustrating an outline of a blade trailing edge portion and a periphery thereof among blades of the centrifugal fan according to the first embodiment.

Fig. 6 is a cross-sectional view showing a cross-section taken along a plane perpendicular to the axial center of the fan in the blade of the centrifugal fan and the periphery thereof in the first embodiment, and fig. 6 is a view showing (a) a cross-section at a portion of the blade trailing edge portion that is connected to the side plate and (b) a cross-section at a portion of the blade trailing edge portion that is connected to the main plate.

Fig. 7A is a graph showing the analysis results of the CFD simulation for confirming the effect of the first embodiment, and is a graph showing the velocity distribution of the air flow in the inter-vane flow path obtained in the case of "Dsi/dso=0.72".

Fig. 7B is a graph showing the analysis result of the CFD simulation, similar to fig. 7A, and is a graph showing the velocity distribution of the air flow in the inter-vane flow path obtained in the case of "Dsi/dso=0.68".

Fig. 7C is a graph showing the analysis result of the CFD simulation, similar to fig. 7A, and is a graph showing the velocity distribution of the air flow in the inter-vane flow path obtained in the case of "Dsi/dso=0.55".

Fig. 7D is a graph showing the analysis result of the CFD simulation, similar to fig. 7A, and is a graph showing the velocity distribution of the air flow in the inter-vane flow path obtained in the case of "Dsi/dso=0.48".

Fig. 8 is a view showing the SPL of noise generated by the blower according to the first embodiment by a solid line S1, and showing the SPL of noise generated by the blower according to the comparative example by a broken line S2.

Fig. 9 is a diagram comparing the noise generated by the blower of the first embodiment with the noise generated by the blower of the comparative example by the overall value.

Fig. 10 is a graph showing a relationship between the noise reduction effect and the ratio of the outer diameter Dmo of the main plate to the other side diameter Db2 of the blade trailing edge portion Dmo 2 in the first embodiment.

Fig. 11 is a longitudinal sectional view schematically showing the blower in a plan view including the fan axis in the second embodiment, and corresponds to fig. 2.

Fig. 12 is a longitudinal sectional view schematically showing the blower in a plane including the fan axis in the third embodiment, and corresponds to fig. 2.

Fig. 13 is a longitudinal sectional view schematically showing the blower in a plane including the fan axis in the fourth embodiment, and corresponds to fig. 2.

Fig. 14 is a vertical sectional view schematically showing the blower in a plane including the fan axis in the fifth embodiment, and corresponds to fig. 2.

Fig. 15 is a vertical sectional view schematically showing the blower in a plan view including the fan axis in the sixth embodiment, and corresponds to fig. 2.

Fig. 16 is a vertical sectional view schematically showing the blower in a plane including the fan axis in the seventh embodiment, and corresponds to fig. 2.

Fig. 17 is a vertical sectional view schematically showing the blower in a plane including the fan axis in the eighth embodiment, and corresponds to fig. 2.

Fig. 18 is a longitudinal sectional view schematically showing the blower in a plane including the fan axis in the ninth embodiment, and corresponds to fig. 2.

Fig. 19 is a vertical sectional view schematically showing the blower in a plane including the fan axis in the tenth embodiment, and corresponds to fig. 2.

Detailed Description

Hereinafter, embodiments will be described with reference to the drawings. In the following embodiments, the same or equivalent portions are denoted by the same reference numerals in the drawings.

(first embodiment)

As shown in fig. 1 and 2, the blower 10 of the present embodiment is a centrifugal blower, and more specifically, a turbine blower. The blower 10 includes a housing 12, a rotation shaft 14, a motor 16, an electronic board 17, a centrifugal fan 28, a bearing housing 29, and the like, which are the frames of the blower 10.

The fan axis CL shown in fig. 2 is a rotation center of the centrifugal fan 18. The arrow Da in fig. 2 indicates the axial direction Da of the fan axis CL, that is, the fan axis direction Da. The arrow Dr in fig. 2 indicates a radial direction Dr of the fan axis CL, that is, a fan radial direction Dr. In fig. 2 and the drawings corresponding to fig. 2 described later, the drawing on the right side of the sheet with respect to the fan axis CL in the blower 10 is omitted.

The housing 12 protects the motor 16, the electronic substrate 17, and the centrifugal fan 18 from dust and dirt outside the blower 10. For this purpose, the casing 12 accommodates the motor 16, the electronic board 17, and the centrifugal fan 18. In addition, the housing 12 is formed of a first housing part 22 and a second housing part 24. The housing 12 is a non-rotating member of the blower 10 that does not rotate.

The first casing member 22 of the casing 12 is made of, for example, resin, has a larger diameter than the centrifugal fan 18, and has a substantially disk shape. The first housing member 22 is composed of a first cover 221, a first housing outer peripheral portion 222, a first peripheral portion 223, and a plurality of struts 224.

The first casing member 22 is a cover that covers the centrifugal fan 18 on the side of the fan axial direction Da of the centrifugal fan 18. Accordingly, the first housing member 22 is disposed on the opposite side of the side plate 34 of the centrifugal fan 18 from the blade 32 side. Further, since the centrifugal fan 18 rotates with respect to the housing 12, the first housing member 22 is disposed away from the side plate 34 of the centrifugal fan 18 in order to prevent mutual interference. The first housing part 22 corresponds to the side panel adjacent housing of the present invention.

The first cover 221 of the first housing member 22 has a shape that expands in the fan radial direction Dr. The first cover 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.

An air intake port 221a penetrating the first cover 221 in the fan axial direction Da is formed on the inner peripheral side of the first cover 221, and air is sucked into the centrifugal fan 18 through the air intake port 221 a. The first cover 221 has a suction port forming portion 221b provided as a flare forming the periphery of the air suction port 221 a. The suction port forming portion 221b forms an air suction port 221a inside the suction port forming portion 221b, and smoothly guides air flowing into the air suction port 221a from outside the blower 10 into the air suction port 221 a.

The first casing outer peripheral portion 222 of the first casing member 22 is disposed outside the first cover 221 in the fan radial direction Dr, and is connected to the first cover 221. The first casing outer periphery 222 is disposed outside the side plate 34 of the centrifugal fan 18 in the fan radial direction Dr. The first housing outer peripheral portion 222 corresponds to the housing outer peripheral portion of the present invention.

As shown in fig. 1 and 2, the first peripheral portion 223 of the first casing member 22 is provided outside the first casing peripheral portion 222 in the fan radial direction Dr, and forms the peripheral edge of the first casing member 22 around the fan axis CL.

The plurality of struts 224 of the first casing member 22 protrude from the first casing outer peripheral portion 222 toward the inside of the casing 12 in parallel with the fan axis CL. The stay 224 has a thick cylindrical shape having a central axis parallel to the fan axis CL. Screw holes through which screws 26 for coupling the first and second case members 22 and 24 are inserted are formed inside the stay 224.

Each of the struts 224 of the first housing member 22 is disposed outside the centrifugal fan 18 in the fan radial direction Dr. In a state where the distal end of the stay 224 abuts against the second housing member 24, the first housing member 22 and the second housing member 24 are coupled by the screw 26 inserted into the stay 224.

The second housing member 24 has a substantially disc shape having substantially the same diameter as the first housing member 22. The second case member 24 is made of metal such as iron or stainless steel, or resin, for example, and also functions as a motor case covering the motor 16 and the electronic board 17. The second case member 24 is constituted by a second cover portion 241, a second case outer peripheral portion 242, and a second peripheral portion 243.

The second cover portion 241 is disposed on the other side in the fan axial direction Da with respect to the centrifugal fan 18 and the motor 16, and covers the other side of the centrifugal fan 18 and the motor 16 in the fan axial direction Da.

The second casing outer peripheral portion 242 of the second casing member 24 is disposed outside the second cover portion 241 in the fan radial direction Dr, and is connected to the second cover portion 241. The second casing outer peripheral portion 242 is disposed outside the main plate 36 of the centrifugal fan 18 in the fan radial direction Dr.

The second casing outer peripheral portion 242 and the first casing outer peripheral portion 222 are formed to face each other in the fan axial direction Da. A fan outer peripheral flow path 12b for allowing air blown out from the outlet 18a of the centrifugal fan 18 to flow outward in the fan radial direction Dr is formed between the second casing outer peripheral portion 242 and the first casing outer peripheral portion 222. The fan outer circumferential flow path 12b is formed around the entire circumference of the centrifugal fan 18.

The second peripheral edge portion 243 of the second casing member 24 is provided outside the second casing outer peripheral portion 242 in the fan radial direction Dr, and forms the peripheral edge of the second casing member 24 around the fan axis CL.

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

Specifically, the air outlet 12a is formed in a fan side surface of the blower 10 and opens outward in the fan radial direction Dr. The air outlet 12a opens over the entire periphery of the housing 12 centered on the fan axis CL, and blows out air from the centrifugal fan 18. That is, the blower 10 is a full-circle blowout blower in which the air outlet 12a is provided over the entire periphery of the casing 12. In addition, since the stay 224 prevents the air from the case 12 from being blown out at the location where the stay 224 is provided, the air outlet 12a opens over the entire circumference of the case 12, which means that the air outlet opens over substantially the entire circumference.

The rotation shaft 14 is made of metal such as iron, stainless steel, or brass. As shown in fig. 2, the rotary shaft 14 is a rod having a cylindrical shape, and is pressed into an inner ring of the bearing 28, for example. Accordingly, the rotary shaft 14 is fixed with respect to the inner wheel of the bearing 28. The outer ring of the bearing 28 is fixed by being pressed into the bearing housing 29, for example. 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.

Therefore, the rotary shaft 14 is supported by the second cover 241 via the bearing 28. That is, the rotation shaft 14 is rotatable about the fan axis CL with respect to the second cover portion 241.

At the same time, the end of the rotating shaft 14 on the side in the fan axial direction Da is fitted into the inner peripheral hole 36a of the main plate 36 of the centrifugal fan 18, whereby the centrifugal fan 18 is fixed to the rotating shaft 14. That is, the centrifugal fan 18 rotates integrally with the rotary shaft 14 around the fan axis CL.

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

The rotor magnet 162 is a permanent magnet, and is made of, for example, a rubber magnet containing ferrite, neodymium element, or the like. The rotor magnet 162 is integrally fixed to the motor rotor 161. The motor rotor 161 is fixed to the rotor coupling portion 38 of the centrifugal fan 18. That is, the motor rotor 161 and the rotor magnet 162 integrally rotate with the centrifugal fan 18 around the fan axis CL.

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 of the rotor magnet 162 with a slight gap therebetween. The motor stator 163 is fixed to the second cover portion 241 of the second housing member 24 via the bearing housing 29. A plurality of electric components, not shown, such as a circuit for driving the motor 16 to rotate, are mounted on the electronic board 17.

In the motor 16 having such a structure, when the stator coil 163a of the motor stator 163 is energized from an external power source, a magnetic flux change is generated in the stator core 163b by the stator coil 163 a. Then, the magnetic flux of the stator core 163b changes to generate a force that attracts the rotor magnet 162. Since the motor rotor 161 is fixed to the rotary shaft 14 rotatably supported by the bearing 28, the motor rotor is rotated about the fan axis CL by the force of attracting the rotor magnet 162. In short, the motor 16 is energized to rotate the centrifugal fan 18 to which the motor rotor 161 is fixed, about the fan axis CL.

As shown in fig. 2 and 3, the centrifugal fan 18 is an impeller applied to the blower 10. The centrifugal fan 18 is rotated around the fan axis CL in a predetermined fan rotation direction DRf to supply air. That is, the centrifugal fan 18 sucks in air from the side in the fan axial direction Da through the air suction port 221a by rotating about the fan axial center CL as indicated by an arrow fli. Then, the centrifugal fan 18 blows out the sucked air to the radial outside of the centrifugal fan 18 as indicated by an arrow FLb.

Specifically, the centrifugal fan 18 of the present embodiment is a turbo fan. The centrifugal fan 18 includes a plurality of blades 32, a side plate 34, a main plate 36, and a rotor coupling portion 38. The centrifugal fan 18 is made of, for example, resin, and is integrally formed with a plurality of blades 32, a side plate 34, a main plate 36, and a rotor connecting portion 38.

The plurality of blades 32 are disposed around the fan axis CL. Specifically, the plurality of blades 32 are arranged in a row in the circumferential direction Dc of the fan axis CL with a space for air flow therebetween. The blades 32 are also referred to as fan blades.

The blades 32 each have a blade one end 321 provided on one side in the fan axial direction Da of the blades 32 and a blade other end 322 provided on the other side opposite to the one side in the fan axial direction Da of the blades 32. The plurality of blades 32 form inter-blade flow paths 32a through which air flows between adjacent blades 32 of the plurality of blades 32.

As shown in fig. 2 and 3, the side plate 34 has a disk-like shape extending in the fan radial direction Dr. Further, an intake hole 34a is formed radially inward of the side plate 34, and the intake hole 34a sucks air from an air intake port 221a of the housing 12 as indicated by an arrow fli. Therefore, the side plate 34 has a ring shape centered on the fan axis CL.

In addition, 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 inside the fan radial direction Dr, and forms the suction hole 34a. The side plate outer peripheral end 342 is an end of the side plate 34 that is disposed outside the fan radial direction Dr. The side plate outer peripheral end 342 corresponds to the outer peripheral end of the present invention provided in the side plate 34.

The side plate 34 is provided on the air intake port 221a side, which is the side in the fan axial direction Da, with respect to the plurality of blades 32. At the same time, the side plate 34 is coupled to each of the plurality of blades 32. In other words, the side plate 34 is connected to each of the blades 32 via one blade end 321.

The side plate 34 has a side plate other surface 343 facing the other side in the fan axial direction Da. The side plate other surface 343 faces the inter-blade flow path 32a, and guides the airflow in the centrifugal fan 18. The side plate other surface 343 is a curved surface extending in the fan radial direction Dr, and is located on the other side in the fan axial direction Da as the side plate other surface is located closer to the outside in the fan radial direction Dr. In the cross section of fig. 2, which is a vertical cross section including the fan axis CL, the radius of curvature of the side plate other surface 343 increases toward the outside in the fan radial direction Dr.

For example, in the present embodiment, in the vertical cross section of the blower 10 shown in fig. 2, the side plate other surface 343 has an inner circular arc shape 343a, an outer circular 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 inner side in the fan radial direction Dr to the inner arc shape 343a, the outer arc shape 343b, and the outer linear shape 343c. 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 straight shape 343c is a straight shape perpendicular to the fan axis CL.

Since the main plate 36 is fixed to the rotation shaft 14 rotatable about the fan axis CL, it is supported rotatably about the fan axis CL with respect to the housing 12. The main plate 36 is shaped to expand in a disk shape in the fan radial direction Dr with the fan axis CL as the center.

The main plate 36 is coupled to each of the plurality of blades 32 on the side opposite to the side plate 34. That is, the main plate 36 is coupled to each of the plurality of blades 32 via the blade other end 322.

In addition, the main plate 36 has a main plate guide surface 36b that guides the air flow in the centrifugal fan 18. The main plate guide surface 36b faces the inter-vane flow path 32a, and faces the side plate other surface 343 with the inter-vane flow path 32a therebetween. The main plate guide surface 36b is a curved surface that extends in the fan radial direction Dr toward one side in the fan axial direction Da, and is formed so as to be located on the other side in the fan axial direction Da as it is located on the outer side in the fan radial direction Dr. With this shape, the main plate guide surface 36b guides the air flow sucked into the air suction port 221a and directed in the fan axial direction Da to the outside in the fan radial direction Dr.

In order to fix the main plate 36 to the rotary shaft 14, an inner peripheral hole 36a penetrating the main plate 36 in the fan axial direction Da is formed radially inward of the main plate 36.

The rotor coupling portion 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 axis direction Da. The motor rotor 161 is fitted into and housed inside the rotor coupling portion 38 in the radial direction. Thereby, the rotor coupling portion 38 is fixed to the motor rotor 161. The centrifugal fan 18 is fixed to the motor rotor 161 by the rotor coupling portion 38 being fixed to the motor rotor 161.

In addition, the main plate 36 has a main plate outer peripheral end 362. The main plate outer peripheral end 362 is an end of the main plate 36 disposed outside the fan radial direction Dr. The main plate outer peripheral end portion 362 and the side plate outer peripheral end portion 342 are disposed apart from each other in the fan axial direction Da. The main plate outer peripheral end portion 362 and the side plate outer peripheral end portion 342 form an air outlet 18a between the main plate outer peripheral end portion 362 and the side plate outer peripheral end portion 342, and the air outlet 18a blows out the air passing through the inter-vane flow path 32 a. That is, the main plate outer peripheral end portion 362 and the side plate outer peripheral end portion 342 constitute an air blowout portion in the centrifugal fan 18 in which the blowout port 18a is formed. The outlet 18a of the centrifugal fan 18 opens outward in the fan radial direction Dr, and is formed over the entire circumference of the centrifugal fan 18 centered on the fan axial center CL.

In the present embodiment, the position of the main plate outer peripheral end 362 in the fan radial direction Dr is aligned with the position of the side plate outer peripheral end 342. That is, as shown in fig. 2 and 4, the outer diameter Dmo of the main plate 36 is the same as the outer diameter Dso of the side plate 34, and is the outer diameter Dout of the centrifugal fan 18.

In addition, the ratio of the inner diameter Dsi of the side plate 34 to the outer diameter Dso of the side plate 34, that is, the inside-outside diameter ratio of the side plate is calculated by Dsi/Dso, and in this embodiment, dsi/Dso is "0.5 < Dsi/Dso < 0.7". In detail, in the present embodiment, dsi/Dso is "Dsi/dso=0.55". The inner diameter Dsi of the side plate 34, in other words, the diameter of the suction hole 34a formed in the side plate 34.

As shown in fig. 2 and 4, the plurality of blades 32 each have a blade leading edge portion 323 provided on the inner side in the fan radial direction Dr and a blade trailing edge portion 324 provided on the outer side in the fan radial direction Dr. The vane leading edge 323 is an edge of the vane 32, which is formed upstream of the air flow direction of the air flowing through the air intake hole 34a to the inter-vane flow path 32 a. The blade trailing edge 324 is an edge of the blade 32, which is formed downstream in the air flow direction of the air flowing through the inter-blade flow path 32 a.

The blade leading edge 323 is connected to the side plate 34 and the main plate 36, and extends from the side plate 34 to the main plate 36. The blade trailing edge 324 is also connected to the side plate 34 and the main plate 36, and extends from the side plate 34 to the main plate 36.

The blade leading edge 323 is formed so as to be located inside the fan radial direction Dr as it is closer to 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 each formed to extend straight, and the first leading edge portion 323a and the second leading edge portion 323b are connected in series. The first leading edge 323a is connected to the side plate 34. The second leading edge 323b is connected to the main plate 36, and is provided between the first leading edge 323a and the main plate 36.

The angle of the second leading edge 323b with respect to the fan axis CL is smaller than the angle of the first leading edge 323a with respect to the fan axis CL. Specifically, in the vertical cross-section of fig. 2 and 4, the first leading edge portion 323a extends straight in a direction perpendicular to the fan axis CL. The second leading edge 323b extends straight and obliquely with respect to the fan axis CL so as to be positioned further outside the fan radial direction Dr as it is closer to the fan axis direction Da.

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 323 b. The diameter Df1 of the second leading edge 323b is a diameter centered on the fan axis CL at one end of the second leading edge 323b in the fan axis direction Da. The other side diameter Df2 of the second leading edge 323b is a diameter centered on the fan axis CL, which is provided at the other side end of the second leading edge 323b in the fan axis direction Da.

The blade trailing edge portion 324 extends so as to be positioned inside the fan radial direction Dr as it is closer to the fan axial direction Da. Specifically, in the vertical cross-sections of fig. 2 and 4, the blade trailing edge 324 is formed in a straight line inclined with respect to the fan axis CL so that the side plate 34 side is positioned inside the main plate 36 side in the fan radial direction Dr.

Therefore, one side diameter Db1 of the blade trailing edge portion 324 is smaller than the other side diameter Db2 of the blade trailing edge portion 324. The one-side diameter Db1 of the blade trailing edge 324 is a diameter centered on the fan axis CL, which is provided at one end of the blade trailing edge 324 in the fan axis direction Da. The other side diameter Db2 of the blade trailing edge 324 is a diameter centered on the fan axis CL, which is provided at the other side end of the blade trailing edge 324 in the fan axis direction Da.

As shown in fig. 2 and 4, the other side diameter Db2 of the blade trailing edge 324 is also the maximum outer diameter of the blade 32 centered on the fan axis CL. The relationship "Db2< dmo.ltoreq.1.13×db2" holds between the other side diameter Db2 of the blade trailing edge 324 and the outer diameter Dmo of the main plate 36. In detail, in the present embodiment, the relationship between the other side diameter Db2 of the blade trailing edge 324 and the outer diameter Dmo of the main plate 36 is "dmo=1.06×db2".

As shown in fig. 2 and 4, a part of the blade leading edge 323 falls within an axial range Hb1, and the axial range Hb1 is included in a full width Hb of the blade trailing edge 324 in the fan axial direction Da. A part of the blade leading edge 323 that enters the axial range Hb1 is, in detail, a part of the end portion of the second leading edge 323b including the main plate 36 side.

The axial height H2 of the side plate other surface 343 extending outward in the fan radial direction Dr from the side plate inner peripheral end 341 with respect to the main plate guide surface 36b along the fan axial direction Da and the outer diameter Dso of the side plate 34 are in a relationship of "0.06 < H2/Dso < 0.20". Specifically, in the present embodiment, the H2/Dso is "H2/dso=0.082".

In the centrifugal fan 18 of the present embodiment, the blade trailing edge portion 324 is connected to the side plate 34 on the inner side of the side plate outer peripheral end portion 342 in the fan radial direction Dr. At the same time, the blade trailing edge 324 is connected to the main plate 36 inside the main plate outer peripheral end 362 in the fan radial direction Dr. That is, the side plate 34 and the main plate 36 extend outside the fan radial direction Dr with respect to the blade trailing edge portion 324, respectively. Specifically, the outer diameter Dso of the side plate 34 and the one-side diameter Db1 of the blade trailing edge 324 have a magnitude relationship of "Dso > Db1", and the outer diameter Dmo of the main plate 36 and the other-side diameter Db2 of the blade trailing edge 324 have a magnitude relationship of "Dmo > Db2".

As described above, since the first housing member 22 is disposed away from the side plate 34 of the centrifugal fan 18, the side plate 34 forms the housing side plate gap 34b with the first housing member 22. For example, the case side plate gap 34b is formed as narrow as possible within a range capable of preventing interference between the first case member 22 and the centrifugal fan 18.

The first casing outer peripheral portion 222 extends from the first cover 221, and is provided so as to overlap the side plate outer peripheral end portion 342 outside the fan radial direction Dr. The inner diameter Dc1 of the first housing outer peripheral portion 222 is larger than the outer diameter Dso of the side plate 34. Accordingly, the side plate outer peripheral end 342 is opposed to the first casing outer peripheral portion 222 in the fan radial direction Dr, and an open end 34c of the casing side plate gap 34b is formed between the side plate outer peripheral end 342 and the first casing outer peripheral portion 222. The opening end 34c of the case side plate gap 34b is located inside the air outlet 12a of the case 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.

In the present embodiment, as shown in fig. 5 and 6, the thickness tb of the blade 32 is not constant in the blade trailing edge portion 324. Specifically, the thickness tb of the blade 32 is larger toward the side plate 34 side in the blade trailing edge portion 324. For example, the thickness tb of the blade 32 at the portion of the blade trailing edge portion 324 that is connected to the side plate 34, that is, the side plate side trailing edge thickness tb1, is larger than the thickness tb of the blade 32 at the portion of the blade trailing edge portion 324 that is connected to the main plate 36, that is, the main plate side trailing edge thickness tb 2.

In this way, in the blade trailing edge portion 324, the thickness tb of the blade 32 varies according to the axial position, and accordingly, the surface shape of the blade trailing edge portion 324 also varies according to the axial position. In fig. 6, the air flow around the vane 32 is shown by a broken line.

In detail, as shown in fig. 6, the blade trailing edge portion 324 has a trailing edge portion outer surface 324a as a surface of the blade trailing edge portion 324. The trailing edge outer surface 324a connects the positive pressure surface and the negative pressure surface of the blade 32 to the blade trailing edge 324, and is convexly curved in a cross section perpendicular to the fan axis CL. Further, in this cross section, the radius of curvature Rb of the trailing edge portion outer surface 324a is larger toward the side plate 34 side. For example, the side plate side radius of curvature Rb, which is the radius of curvature Rb of the trailing edge portion outer surface 324a at the portion of the blade trailing edge portion 324 that 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 that is connected to the main plate 36.

Fig. 5 shows a blade trailing edge 91 of a centrifugal fan of a comparative example compared with the present embodiment, in broken lines. In the centrifugal fan of this comparative example, the blade trailing edge portion 91 is parallel to the fan axis CL, and the thickness tb of the blade 32 in the blade trailing edge portion 91 is constant. Except for this, the centrifugal fan of the comparative example is the same as the centrifugal fan 18 of the present embodiment.

As shown in fig. 2 and 3, the centrifugal fan 18 configured as described above rotates in the fan rotation direction DRf integrally with the motor rotor 161. Accordingly, since the blades 32 of the centrifugal fan 18 impart momentum to the air, the centrifugal fan 18 sucks air from the suction holes 34a as indicated by arrows fli, and the sucked air flows radially outward in the inter-blade flow paths 32a as indicated by arrows FL1, FL2, and FL 3. Then, the centrifugal fan 18 blows out the air having passed through the inter-blade flow path 32a from the air outlet 18a to the radially outer side as indicated by an arrow FLb. The air blown out from the air outlet 18a passes through the fan outer peripheral flow path 12b of the casing 12, and is released from the air outlet 12a to the outside of the blower 10.

As described above, according to the present embodiment, as shown in fig. 2 and 4, in each of the plurality of blades 32, the blade trailing edge portion 324 is formed so as to be located inside the fan radial direction Dr as it is closer to the fan axial direction Da.

Here, the air flow in the inter-vane flow path 32a formed between the vanes 32 will be described, and the air flow in the inter-vane flow path 32a is temporarily separated from the side plate 34 on the upstream side of the inter-vane flow path 32a as indicated by arrow FL1, and a vortex WH is generated on the side plate other surface 343. Then, the air flow in the inter-vane flow path 32a is once peeled off from the side plate 34 as described above, and then proceeds as indicated by arrow FL 2. That is, the air flow is biased to one side in the fan axial direction Da so as to be once separated from the side plate 34 and then attached to the side plate 34 again.

In contrast, in the centrifugal fan 18 of the present embodiment, as described above, the blade trailing edge portion 324 is formed so as to be located further toward the fan axial direction Da than toward the inner side in the fan radial direction Dr, and therefore the amount of work performed on the main plate 36 side by each blade 32 is greater than on the side plate 34 side. As a result, the air flow can be sucked again toward the main plate 36 as indicated by arrow FL3 near the outlet of the inter-vane flow path 32 a. 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 in the vicinity of the outlet of the inter-blade flow path 32a can be made closer to the distribution which is not deviated in the fan axis direction Da, and the noise of the centrifugal fan 18 can be reduced.

In the centrifugal fan 18, the ratio Dsi/Dso 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". Accordingly, for the centrifugal fan in which the air flow in the inter-blade flow path 32a is biased toward the side plate 34 side in the vicinity of the outlet of the inter-blade flow path 32a assuming that the blade trailing edge portion 324 is parallel to the fan axial center CL, the above-described configuration can be used in which the side of the blade trailing edge portion 324 in the fan axial center direction Da is positioned further toward the inside in the fan radial direction Dr. Therefore, in order to properly reduce noise of the centrifugal fan 18, the above-described structure of the blade trailing edge portion 324 of the present embodiment can be used.

When Dsi/Dso is, for example, 0.5 or less, the length of the inter-blade flow path 32a is sufficiently long after the air flow is deviated to one side in the fan axial direction Da as indicated by arrow FL 2. Therefore, even if the blade trailing edge 324 is assumed to be parallel to the fan axis CL, the deviation of the air flow to the side in the fan axis direction Da is relaxed after the air flow is deviated to the side in the fan axis direction Da and before the air flow reaches the blade trailing edge 324. 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 offset to one side in the fan axial direction Da so as to be reattached to the side plate 34. In short, the air flows indicated by arrows FL1 and FL2 are cut off halfway. Therefore, in order to effectively reduce noise of the centrifugal fan 18, the above-described structure in which the blade trailing edge portion 324 is located further toward the fan axial direction Da than the inner side in the fan radial direction Dr is necessary, the relationship "0.5 < Dsi/Dso < 0.7".

For example, analysis results are obtained by changing the size of Dsi/Dso through simulation of CFD, and it has been confirmed that the relationship of "0.5 < Dsi/Dso < 0.7" is necessary. CFD is an abbreviation for "Computational Fluid Dynamics (computational fluid dynamics)". In the centrifugal fan of this example, the configuration of the blades 32 is the same as that of the comparative example. That is, in the centrifugal fan of the simulation example, the blade trailing edge portion 91 (see fig. 5) is parallel to the fan axis CL, and the thickness tb of the blade 32 in the blade trailing edge portion 91 is constant. Except for this point, the centrifugal fan of this simulation example is the same as the centrifugal fan 18 of the present embodiment.

The analysis results obtained from the CFD simulation are shown in fig. 7A to 7D. In this simulation, the rotational speed of the centrifugal fan is constant. In fig. 7A to 7D, arrows A1 and A2 indicate the direction of air flow in the inter-vane flow path 32 a. The position P1 represents a position where the side plate 34 faces the inter-vane flow path 32a, and the position P2 represents a position where the main plate 36 faces the inter-vane flow path 32 a. In fig. 7A to 7D, the difference in the speed (in other words, the flow velocity) of the air flow in the inter-vane flow path 32a is represented by hatching.

Specifically, fig. 7A shows the velocity distribution of the air flow in the inter-vane flow path 32a obtained in the case of "Dsi/dso=0.72". According to fig. 7A, in the case of "Dsi/dso=0.72", the high-speed portion is offset to the other side (i.e., the main plate 36 side) in the fan axial direction Da in the velocity distribution of the air flow in the vicinity of the outlet of the inter-blade flow path 32a (i.e., in the vicinity of the blade trailing edge portion 91 in fig. 5).

Fig. 7B shows the velocity distribution of the air flow in the inter-vane flow path 32a obtained in the case of "Dsi/dso=0.68", and fig. 7C shows the velocity distribution of the air flow in the inter-vane flow path 32a obtained in the case of "Dsi/dso=0.55". According to fig. 7B and 7C, in the velocity distribution of the air flow in the vicinity of the outlet of the inter-blade flow path 32a, in the case of "Dsi/dso=0.68" and in the case of "Dsi/dso=0.55", the high-velocity portion is offset to one side (i.e., the side plate 34 side) in the fan axial direction Da.

Fig. 7D shows the velocity distribution of the air flow in the inter-vane flow path 32a obtained in the case of "Dsi/dso=0.48". According to fig. 7D, in the case of "Dsi/dso=0.48", there is no deviation in the fan axial direction Da in the velocity distribution of the air flow in the vicinity of the outlet of the inter-blade flow path 32 a.

The following can be obtained from the velocity distribution of the air flow shown in fig. 7A to 7D. That is, as shown in fig. 7B and 7C, in the case where "0.5 < Dsi/Dso < 0.7", if the blade trailing edge portion 324 is inclined with respect to the fan axial direction Da as in the present embodiment, the velocity distribution of the air flow in the vicinity of the outlet of the inter-blade flow path 32a approaches the velocity distribution without the deviation of the fan axial direction Da. This is because, as in the present embodiment, the blade trailing edge portion 324 (see fig. 2) inclined with respect to the fan axial direction Da functions to attract air toward the main plate 36 side in the vicinity of the outlet of the inter-blade flow path 32a as described above, as compared with the blade trailing edge portion 91 parallel to the fan axial direction CL. Therefore, in this case, the inclination of the blade trailing edge 324 with respect to the fan axial direction Da causes the reduction of noise of the centrifugal fan 18 as in the present embodiment.

On the other hand, in fig. 7A and 7D, in the velocity distribution of the air flow in the vicinity of the outlet of the inter-vane flow path 32a, the high-velocity portion is not deviated toward the side plate 34 side. Therefore, in the case of "0.7. Ltoreq.dsi/Dso" and in the case of "Dsi/Dso. Ltoreq.0.5", even if the air flow direction in the vicinity of the outlet of the inter-blade flow path 32a is sucked toward the main plate 36 side, the velocity distribution of the air flow in the vicinity of the outlet does not come close to the case where there is no deviation in the fan axial direction Da. That is, in this case, even if the blade trailing edge 324 is inclined with respect to the fan axial direction Da as in the present embodiment, the centrifugal fan 18 does not have a low noise.

As described above, from the analysis results of fig. 7A to 7D, in order to effectively reduce noise of the centrifugal fan 18 by the configuration in which the blade trailing edge 324 is inclined with respect to the fan axial direction Da as in the present embodiment, it can be said that the relationship "0.5 < Dsi/Dso < 0.7" is necessary.

In contrast to the centrifugal fan 18 of the present embodiment and the centrifugal fan of the comparative example in which the blade trailing edge 91 (see fig. 5) is parallel to the fan axis CL, the centrifugal fan 18 is reduced in noise in almost all frequency ranges as shown in fig. 8. In fig. 8, a solid line S1 represents SPL of the present embodiment, and a broken line S2 represents SPL of the comparative example. SPL is an abbreviation for "Sound Pressure Level (sound pressure level)".

In addition, as shown in fig. 9, in the present embodiment, the noise of the centrifugal fan 18 is reduced by 2dB as compared with the comparative example. The vertical axis of fig. 9, "o.a." is an abbreviation for the overall (Over All) value.

(1) In addition, according to the present embodiment, the side plate other surface 343 is located on the other side in the fan axial direction Da as it is located on the outer side in the fan radial direction Dr. In the vertical cross-section of fig. 2 and 4, the radius of curvature of the side plate other surface 343 increases toward the outside in the fan radial direction Dr. Accordingly, the noise reduction effect due to the structure in which the blade trailing edge portion 324 is positioned further toward the fan axial direction Da than the inner side in the fan radial direction Dr can be obtained, and the air sucked into the centrifugal fan 18 from the side in the fan axial direction Da can be guided to the outer side in the fan radial direction Dr.

(2) In addition, according to the present embodiment, as shown in fig. 2 and 4, in each of the plurality of blades 32, 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 located inside the fan radial direction Dr as approaching the main plate 36. Therefore, since the length of the blade 32 is longer on the main plate 36 side than on the side plate 34 side, the work done on the main plate 36 side by each blade 32 can be made larger than on the side plate 34 side. Accordingly, the air flow in the inter-blade flow path 32a can be corrected to be deviated to one side in the fan axial direction Da.

(3) In addition, according to the present embodiment, the side plate 34 and the main plate 36 extend outside the fan radial direction Dr, respectively, than the blade trailing edge portion 324. Therefore, the blade trailing edge portion 324, which maximizes the flow velocity of the air stream, can be located away from the open end 34c of the case side plate gap 34 b. This is advantageous in achieving low noise of the centrifugal fan 18.

Further, since the side plate 34 and the main plate 36 extend further outward in the fan radial direction Dr than the blade trailing edge portion 324, the air flow can be suppressed from expanding sharply in the fan axial direction Da immediately after flowing out from the inter-blade flow path 32 a. This can suppress loss due to rapid expansion of the air flow, and contribute to the reduction of noise of the centrifugal fan 18.

For example, a relationship between Dmo/Db2, which is a ratio of the outer diameter Dmo of the main plate 36 to the other side diameter Db2 of the blade trailing edge portion 324, and the noise reduction effect is shown in FIG. 10. That is, the larger Dmo/Db2, the higher the noise reduction effect. As can be seen from fig. 10, the side plate 34 and the main plate 36 extend outside the blade trailing edge 324 in the fan radial direction Dr, and serve to improve the noise reduction effect. In the experiment of fig. 10, the outer diameter Dso of the side plate 34 was the same as the outer diameter Dmo of the main plate 36.

(4) In addition, according to the present embodiment, the relationship of "Db2< dmo+.1.13×db2" is established between the other side diameter Db2 of the blade trailing edge portion 324 and the outer diameter Dmo of the main plate 36. Further, according to fig. 10, when dm o/Db2 exceeds 1.13, the noise reduction effect increases more gradually as dm o/Db2 increases, but the noise reduction effect does not change much with respect to dm o/Db 2. Therefore, the centrifugal fan 18 can be prevented from being larger than necessary, and a noise reduction effect can be obtained.

(5) Further, according to the present embodiment, the first casing outer peripheral portion 222 of the first casing member 22 is provided so as to overlap with the side plate outer peripheral end portion 342 of the centrifugal fan 18 outside the fan radial direction Dr. The side plate outer peripheral end 342 faces the first casing outer peripheral portion 222 in the fan radial direction Dr, and an opening end 34c of the casing side plate gap 34b is formed between the side plate outer peripheral portion 222 and the first casing outer peripheral portion 222.

Accordingly, the open end 34c of the case-side plate gap 34b is located inside the air outlet 12a of the case 12 in the fan radial direction Dr, and therefore the air pressure at the open end 34c is lower than the air pressure at the air outlet 12 a. Thus, for example, the backflow of the blown air flowing into the case side plate gap 34b from the open end 34c can be suppressed as compared with a case where the open end 34c is opened outside the air outlet 12 a.

(6) In addition, according to the present embodiment, as shown in fig. 4 to 6, the blade trailing edge portion 324 extends from the side plate 34 side to the main plate 36 side, and the thickness tb of the blade 32 increases toward the side plate 34 side in the blade trailing edge portion 324. Therefore, since the stall region ST of the air flow adjacent to the blade trailing edge 324 is larger on the side plate 34 side than on the main plate 36 side, the air flow loss due to the stall region ST increases toward the side plate 34 side. This also serves to suppress the air flow around the blade trailing edge 324 from being biased to one side in the fan axial direction Da.

(7) In addition, according to the present embodiment, as shown in fig. 5 and 6, in a cross section perpendicular to the fan axis CL (for example, a cross section of 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 increases toward the side plate 34. Therefore, the positive pressure surface and the negative pressure surface of the blade 32 can be smoothly connected by the blade trailing edge portion 324. Therefore, the flow resistance of the air around the blade trailing edge 324 can be ensured to be larger on the side plate 34 side than on the main plate 36 side, and the entire flow resistance can be reduced as compared with the case where the positive pressure surface and the negative pressure surface are not smoothly connected by the blade trailing edge 324.

(second embodiment)

Next, a second embodiment will be described. In this embodiment, points different from the first embodiment described above will be mainly described. The same or equivalent parts as those of the above embodiments will be omitted or briefly described. This is also the case in the description of the embodiment described below.

As shown in fig. 11, in the present embodiment as well, the blade trailing edge portion 324 is formed so as to be located inside the fan radial direction Dr as it is closer to the fan axial direction Da. However, in the present embodiment, the shape of the blade trailing edge portion 324 is different from that of the first embodiment.

Specifically, the blade trailing edge portion 324 of the present embodiment is formed to have a single step shape, and is located stepwise inside the fan radial direction Dr as it is closer to the fan axial direction Da.

The present embodiment is the same as the first embodiment except for the above description. In the present embodiment, the same effects as those achieved by the structure common to the first embodiment can be obtained as in the first embodiment.

(third embodiment)

Next, a third embodiment will be described. In this embodiment, mainly, the differences from the first embodiment described above will be described.

As shown in fig. 12, in the present embodiment as well, the blade trailing edge portion 324 is formed so as to be located inside the fan radial direction Dr as it is closer to the fan axial direction Da. However, in the present embodiment, the shape of the blade trailing edge portion 324 is different from that of the first embodiment.

Specifically, the blade trailing edge portion 324 of the present embodiment is formed to have a plurality of stepped shapes, and is located stepwise inside the fan radial direction Dr as it is closer to the fan axial direction Da.

(fourth embodiment)

Next, a fourth embodiment will be described. In this embodiment, points different from the first embodiment described above will be mainly described.

As shown in fig. 13, in the present embodiment as well, the blade trailing edge portion 324 is formed so as to be located inside the fan radial direction Dr as it is closer to the fan axial direction Da. However, in the present embodiment, the shape of the blade trailing edge portion 324 is different from that of the first embodiment.

Specifically, the blade trailing edge 324 of the present embodiment extends parallel to the fan axis CL at a portion of the blade trailing edge 324 on one side in the fan axis direction Da including a portion connected to the side plate 34. The blade trailing edge 324 is inclined with respect to the fan axis CL so that the other side in the fan axis direction Da is located further outward in the fan radial direction Dr than the other side in the fan axis direction Da, at a portion of the blade trailing edge 324 including the portion connected to the main plate 36.

(fifth embodiment)

Next, a fifth embodiment will be described. In this embodiment, points different from the first embodiment described above will be mainly described.

As shown in fig. 14, in the present embodiment as well, the blade trailing edge portion 324 is formed so as to be located inside the fan radial direction Dr as it is closer to the fan axial direction Da. However, in the present embodiment, the shape of the blade trailing edge portion 324 is different from that of the first embodiment.

Specifically, the blade trailing edge portion 324 of the present embodiment extends while being curved.

(sixth embodiment)

Next, a sixth embodiment will be described. In this embodiment, points different from the first embodiment described above will be mainly described.

As shown in fig. 15, in the present embodiment as well, the side plate other surface 343 of the centrifugal fan 18 extends toward the other side in the fan axial direction Da and extends in the fan radial direction Dr, and is positioned on the other side in the fan axial direction Da as it approaches the outer side 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.

Specifically, in the vertical cross section of the blower 10 shown in fig. 15, the side plate other surface 343 has an inner circular arc shape 343a and an outer linear shape 343d. The outer linear shape 343d is replaced with the outer circular arc shape 343b and the outer linear shape 343c (see fig. 2) of embodiment 1

In the vertical cross section of fig. 15, the inner arc shape 343a and the outer linear shape 343d of the present embodiment are smoothly connected in the order of the inner arc shape 343a and the outer linear shape 343d from the inside in the fan radial direction Dr. The outer linear shape 343d is formed in a linear shape inclined with respect to the fan axis CL so as to be located on the other side in the fan axis direction Da as the outer side in the fan radial direction Dr is located. Thus, in the vertical cross section of fig. 15, the side plate other surface 343 of the present embodiment is formed by a circular arc and a straight line.

Although the present embodiment is based on the modification of the first embodiment, the present embodiment may be combined with any one of the second to fifth embodiments described above.

(seventh embodiment)

Next, a seventh embodiment will be described. In this embodiment, points different from the first embodiment described above will be mainly described.

As shown in fig. 16, in the present embodiment as well, the side plate other surface 343 of the centrifugal fan 18 extends toward the other side in the fan axial direction Da and extends toward the fan radial direction Dr, and is positioned on the other side in the fan axial direction Da as it approaches the outer side 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.

Specifically, in the vertical cross section of the blower 10 shown in fig. 16, the side plate other surface 343 is formed in a straight line inclined with respect to the fan axis CL so as to be located on the other side in the fan axis direction Da as it is located closer to the outside in the fan radial direction Dr. As described above, in the vertical cross section of fig. 16, the side plate other surface 343 of the present embodiment is formed of a straight line.

(1) Accordingly, the noise reduction effect due to the structure in which the blade trailing edge portion 324 is located further toward the fan axial direction Da than the inner side in the fan radial direction Dr can be obtained, and the air sucked into the centrifugal fan 18 from the side in the fan axial direction Da can be guided to the outer side in the fan radial direction Dr.

(eighth embodiment)

Next, an eighth embodiment will be described. In this embodiment, points different from the first embodiment described above will be mainly described.

As shown in fig. 17, in the present embodiment as well, the side plate other surface 343 of the centrifugal fan 18 extends toward the other side in the fan axial direction Da and extends toward the fan radial direction Dr, and is positioned on the other side in the fan axial direction Da as it approaches the outer side 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.

Specifically, in the vertical cross section of the blower 10 shown in fig. 17, the side plate other surface 343 is formed in an arc shape extending so as to be located on the other side in the fan axial direction Da as it is located on the outer side in the fan radial direction Dr. Thus, in the vertical cross section of fig. 17, the side plate other surface 343 of the present embodiment is formed of an arc.

(ninth embodiment)

Next, a ninth embodiment will be described. In this embodiment, points different from the first embodiment described above will be mainly described.

As shown in fig. 18, in the present embodiment as well, the blade leading edge 323 extends from the side plate 34 side to the main plate 36 side, and is formed so as to be located further inward in the fan radial direction Dr than toward the main plate 36 side. However, in the present embodiment, the shape of the blade leading edge portion 323 is different from that of the first embodiment.

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

The third leading edge 323c is connected to the main plate 36, and is provided between the second leading edge 323b and the main plate 36. The third leading edge 323c is formed parallel to the fan axis CL in the vertical cross section of fig. 18.

Although the present embodiment is based on the modification of the first embodiment, the present embodiment may be combined with any one of the second to eighth embodiments described above.

(tenth embodiment)

Next, a tenth embodiment will be described. In this embodiment, points different from the first embodiment described above will be mainly described.

As shown in fig. 19, the motor 16 of the present embodiment includes a motor rotor 40 instead of the motor rotor 161 (see fig. 2) of the first embodiment. The centrifugal fan 18 of the present embodiment has a main plate outer peripheral 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 plurality of blades 32, the side plates 34, the main plate outer peripheral portion 43, and the rotor coupling portion 44 are integrally formed.

Specifically, the motor rotor 40 of the present embodiment has an inner peripheral hole 40a corresponding to the inner peripheral hole 36a of the first embodiment, and the rotary shaft 14 is fitted into the inner peripheral hole 40a. Thus, the motor rotor 40 is directly fixed to the rotary shaft 14, and rotates integrally with the rotary shaft 14 around the fan axis CL.

The motor rotor 40 has a main plate inner peripheral portion 401 and a cylindrical portion 402. The main plate inner peripheral portion 401 is formed in a disk-like shape extending in the fan radial direction Dr around the fan axial center CL. Further, the main plate inner peripheral portion 401 has an inner Zhou Zhuban surface 401a. The inner Zhou Zhuban surface 401a is a curved surface extending in the fan radial direction Dr toward one side in the fan axial direction Da, and is formed so as to be located on the other side in the fan axial direction Da as it is located on the outer side 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 air sucked by the centrifugal fan 18, and thus is a part of the centrifugal fan 18.

In fig. 19, a gap is shown between the blade 32 and the main plate inner peripheral portion 401 of the motor rotor 40, which is a diagram for convenience of judgment. Each blade 32 may be in contact with the main plate inner peripheral portion 401 or may be separated from the main plate inner peripheral portion 401 with a gap therebetween as shown in the drawing.

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

The main plate outer peripheral portion 43 is disposed outside the main plate inner peripheral portion 401 in the fan radial direction Dr, and has a disk-like shape extending in the fan radial direction Dr with the fan axial center CL as the center. Specifically, the main plate outer peripheral portion 43 has a shape that continuously extends outward in the fan radial direction Dr from the main plate inner peripheral portion 401. Therefore, the main board outer peripheral portion 43 and the main board inner peripheral portion 401 correspond to the main board 36 (see fig. 2) of the first embodiment as a whole.

The main plate outer peripheral portion 43 has an outer peripheral main plate surface 43a facing one side in the fan axial direction Da. The outer peripheral main plate surface 43a continuously extends outward in the fan radial direction Dr from the inner Zhou Zhuban surface 401 a. The other end portions 322 of the plurality of blades 32 are connected to the outer Zhou Zhuban surfaces 43a, respectively. The outer peripheral main plate surface 43a and the inner Zhou Zhuban surface 401a integrally form a main plate guide surface 36b that guides the air flow in the centrifugal fan 18.

The main plate outer peripheral portion 43 has an outer peripheral end portion 431 as an end portion provided outside the fan radial direction Dr. The outer peripheral end 431 corresponds to the main board outer peripheral end 362 (see fig. 2) of the first embodiment.

The rotor connection portion 44 has a cylindrical shape centered on the fan axial center CL, and extends from a radially inner end of the main plate outer peripheral portion 43 to the other side in the fan axial center direction Da. The cylindrical portion 402 of the motor rotor 40 is fitted into the radially inner side of the rotor coupling portion 44. Thereby, the rotor coupling portion 44 is fixed to the motor rotor 40. Further, by fixing the rotor coupling portion 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.

Although the present embodiment is based on the modification of the first embodiment, the present embodiment may be combined with any one of the second to ninth embodiments described above.

(other embodiments)

(1) In the above embodiments, the centrifugal fan 18 is a turbo fan as shown in fig. 2, but may be another type of centrifugal fan such as a radial fan.

(2) In the above embodiments, as shown in fig. 2, the motor 16 is an outer rotor type brushless DC motor, but is not limited to this motor form. For example, the motor 16 may be an inner rotor type motor or a brush motor.

(3) In the above embodiments, the second leading edge portion 323b extends linearly in the vertical cross section of fig. 2 and 4, but may be curved.

(4) In the first embodiment described above, as shown in fig. 2, the outer diameter Dmo of the main plate 36 is the same as the outer diameter Dso of the side plate 34, but this is 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.

(5) The present invention is not limited to the above-described embodiments, and can be variously modified and implemented. In addition, the above embodiments are not unconnected to each other, and can be appropriately combined except for the case where combination is obviously impossible.

In the above embodiments, the elements constituting the embodiments are not necessarily required, except when they are particularly clearly shown to be required, when they are obviously considered to be required in principle, or the like. In the above embodiments, the numbers, values, amounts, ranges, and the like of the constituent elements of the embodiments are not limited to a specific number, except when necessary for particular clarity and when, in principle, the number is obviously limited to the specific number. In the above embodiments, the materials, shapes, positional relationships, and the like of the constituent elements and the like are mentioned, but the materials, shapes, positional relationships, and the like are not limited thereto, except for the cases where they are specifically indicated and the cases where they are limited to specific materials, shapes, positional relationships, and the like in principle.

(features of the invention)

[ first viewpoint ]

A centrifugal fan that sucks air from one side in an axial direction (Da) of a fan axis (CL) by rotating the centrifugal fan around the fan axis and blows the sucked air out of a radial direction (Dr) of the fan axis, characterized by comprising:

A plurality of blades (32) arranged around the fan axis and having blade trailing edge portions (324) on the outer side in the radial direction;

a side plate (34) that forms an intake hole (34 a) for sucking air, is provided on the one side in the axial direction with respect to the plurality of blades, and is connected to each of the plurality of blades; and

a main plate (36, 43, 401) connected to each of the plurality of blades on a side opposite to the side plate side, and extending in the radial direction,

with the inner diameter of the side plate being Dsi and the outer diameter of the side plate being Dso, dsi/Dso is 0.5 < Dsi/Dso < 0.7,

the blade trailing edge portion is formed so as to be located radially inward of the one side in the axial direction.

[ second viewpoint ]

According to the centrifugal fan of the first aspect, the side plate has a side plate other surface (343) which faces the other side opposite to the one side in the axial direction and expands in the radial direction,

the closer the other side of the side plate is to the radial outside the other side in the axial direction,

in a vertical section including the fan axis, the radius of curvature of the other surface of the side plate increases as the other surface approaches the outer side in the radial direction.

Third viewpoint ]

in the longitudinal section including the axial center of the fan, the other surface of the side plate is formed by an arc or a straight line.

[ fourth viewpoint ]

The centrifugal fan according to any one of the first to third aspects, wherein each of the plurality of blades has a blade leading edge portion (323) on the inner side in the radial direction,

the blade leading edge portion extends from the side plate side toward the main plate side, and is formed so as to be located inside in the radial direction as it is closer to the main plate side.

[ fifth viewpoint ]

According to the centrifugal fan of the fourth aspect, a part of the blade leading edge portion is included in an axial range (Hb 1) which is included in the entire width (Hb) of the blade trailing edge portion in the axial direction.

[ sixth viewpoint ]

The centrifugal fan according to any one of the first to fifth aspects, wherein the side plate and the main plate extend outward in the radial direction from the blade trailing edge portion.

Seventh viewpoint ]

The centrifugal fan according to any one of the first to sixth aspects, wherein the side plate and the main plate extend outward in the radial direction from the blade trailing edge portion,

when the maximum outer diameter of the plurality of blades is Db2 and the outer diameter of the main plate is Dmo, db2 < Dmo.ltoreq.1.13×Db2 holds.

Eighth viewpoint ]

The centrifugal fan according to any one of the first to seventh aspects, which constitutes a part of the blower (10),

the blower has a side plate adjacent housing (22) which is arranged on the side opposite to the blade side relative to the side plate and is arranged separately from the side plate,

the side plate has an outer peripheral end portion (342) disposed on the outer side in the radial direction, a case side plate gap (34 b) is formed between the side plate and the case adjacent to the side plate,

the side plate adjacent housing has a housing outer peripheral portion (222) provided so as to overlap with an outer peripheral end portion of the side plate on the outer side in the radial direction,

the outer peripheral end portion of the side plate and the housing outer peripheral portion are opposed to each other in the radial direction, and an opening end (34 c) of the housing side plate gap is formed between the outer peripheral end portion of the side plate and the housing outer peripheral portion.

[ ninth viewpoint ]

The centrifugal fan according to any one of the first to eighth aspects, wherein the blade trailing edge portion extends from the side plate side to the main plate side,

the thickness (tb) of the plurality of blades is greater in the blade trailing edge portion closer to the side plate side, respectively.

Tenth viewpoint ]

According to the centrifugal fan of the ninth aspect, in a cross section perpendicular to the fan axis, the blade trailing edge portion has a convexly curved trailing edge portion outer surface (324 a), and the radius of curvature (Rb) of the trailing edge portion outer surface increases as it approaches the side plate side.

Claims

1. A centrifugal fan that sucks air from one side in an axial direction (Da) of a fan axis (CL) by rotating the centrifugal fan around the fan axis and blows the sucked air out of a radial direction (Dr) of the fan axis, characterized by comprising:

2. The centrifugal fan according to claim 1, wherein,

the side plate has a side plate other surface (343) which faces the other side opposite to the one side in the axial direction and expands in the radial direction,

3. The centrifugal fan according to claim 1, wherein,

4. A centrifugal fan according to any one of claims 1 to 3,

The plurality of blades each have a blade leading edge portion (323) on the radially inner side,

5. The centrifugal fan according to claim 4, wherein,

a part of the blade leading edge portion is included in an axial range (Hb 1) which is included in the full width (Hb) of the blade trailing edge portion in the axial direction.

6. A centrifugal fan according to any one of claims 1 to 3,

the side plate and the main plate extend to the outside in the radial direction than the blade trailing edge portion, respectively.

7. A centrifugal fan according to any one of claims 1 to 3,

the side plates and the main plate extend to the outside in the radial direction than the blade trailing edge portions,

8. A centrifugal fan according to any one of claims 1 to 3,

the centrifugal fan forms part of a blower (10),

9. A centrifugal fan according to any one of claims 1 to 3,

the blade trailing edge portion extends from the side plate side to the main plate side,

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 portion outer surface (324 a) having a radius of curvature (Rb) that increases as it approaches the side plate side.