Impeller and axial flow fan

Abstract

The impeller has: a main body that rotates about a central axis extending axially; and a plurality of blades that project radially from the outer peripheral surface of the main body and are arranged at circumferential intervals. By rotating the blades about the central axis, airflow is generated in the axial direction. In the impeller, in a cross-section of at least one of the blades that includes the central axis and extends radially, the axial width first increases briefly from the radially inward side and then decreases from the radially outward side. Taking the axial side as the intake side, the edge of the axial side of the cross-section has a convex shape projecting towards the axial side. When viewed axially, the cross-section intersects the radially inner edge of the blade.

Description

Technical Field

[0001] This disclosure relates to an impeller. Background Technology

[0002] Previously, an impeller used in axial flow fans was known. The impeller has a hub and a plurality of blades fixed on the hub (e.g., Patent Document 1).

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: U.S. Patent Application Publication No. 2017 / 0167508 Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] There is still room for improvement in the air delivery efficiency of the aforementioned impeller.

[0008] The purpose of this disclosure is to provide an impeller that can improve air delivery efficiency and an axial flow fan having the impeller.

[0009] Solution for solving the problem

[0010] An exemplary impeller of this disclosure has: a main body that rotates about a central axis extending axially; and a plurality of blades that project radially from the outer peripheral surface of the main body and are arranged at circumferential intervals. By rotating the blades about the central axis, an axially flowing wind is generated. In the impeller, in at least one cross-section of at least one of the blades that includes the central axis and extends radially, the axial width first increases briefly from the radially inner side to the radially outer side and then decreases, with the axial side serving as the air intake side. The edge of the axial side of the cross-section has a convex shape that projects towards the axial side. When viewed axially, the cross-section intersects the radially inner edge of the blade.

[0011] Invention Effects

[0012] According to the exemplary impeller of this disclosure, air delivery efficiency can be improved. Attached Figure Description

[0013] Figure 1 This is a perspective view of an axial flow fan according to an exemplary embodiment of the present disclosure, viewed from above.

[0014] Figure 2 This is a longitudinal sectional view of an axial flow fan according to an exemplary embodiment of this disclosure.

[0015] Figure 3 This is a perspective view of an impeller according to an exemplary embodiment of the present disclosure.

[0016] Figure 4 yes Figure 3 The impeller shown is viewed from the top as an axial direction.

[0017] Figure 5 express Figure 4 A schematic partial sectional view of the AA line section shown.

[0018] Figure 6 Is with Figure 5 Same sectional view. Detailed Implementation

[0019] Hereinafter, exemplary embodiments of the present disclosure will be described with reference to the accompanying drawings.

[0020] In this specification, in the axial flow fan 1, the direction parallel to the central axis J of the impeller 3 (described later) is referred to as the "axial direction". Within the axial direction, the intake side is referred to as "axial side Da", and the exhaust side as "axial side Db". Furthermore, the direction orthogonal to the central axis J is referred to as the "radial direction". Within the radial direction, the direction closer to the central axis J is referred to as the "radial inner direction", and the direction farther from the central axis J is referred to as the "radial outer direction". Additionally, the direction of rotation centered on the central axis J is referred to as the "circumferential direction Dc".

[0021] It should be noted that these are for illustrative purposes only and are not intended to limit actual positional relationships, directions, or names.

[0022] <Composition of Axial Flow Fans>

[0023] Figure 1 This is a perspective view of an axial flow fan 1 according to an exemplary embodiment of the present disclosure, viewed from above. Figure 2 This is a longitudinal sectional view of an axial flow fan 1 according to an exemplary embodiment of this disclosure.

[0024] The axial flow fan 1 has a motor 2, an impeller 3, and a casing 4.

[0025] The motor 2 is positioned radially inward of the housing 4. The motor 2 is supported on the motor base 41 of the housing 4. The motor 2 causes the impeller 3 to rotate about the axially extending central axis J. That is, the axial flow fan 1 has an impeller 3 and a motor 2 that drives the impeller 3 to rotate.

[0026] The motor 2 has a stator 23 and a rotor 24. More specifically, the motor 2 has a bearing 21, a shaft 22, a stator 23, a rotor 24, and a circuit board 25.

[0027] The bearing 21 is held inside the cylindrical bearing retainer 412 on the motor base portion 41. The bearing 21 is a sleeve bearing. It should be noted that the bearing 21 may also be a pair of ball bearings arranged vertically.

[0028] Shaft 22 is arranged along the central axis J. Shaft 22 is made of metal such as stainless steel and is a columnar member extending axially. Shaft 22 is supported by bearing 21 so that it can rotate about the central axis J.

[0029] The stator 23 is fixed to the outer peripheral surface of the bearing retaining part 412 of the motor base part 41. The stator 23 has a stator core 231, an insulator 232, and a coil 233.

[0030] The stator core 231 is constructed by stacking electromagnetic steel sheets, such as silicon steel sheets, in the vertical direction. The insulating member 232 is made of insulating resin. The insulating member 232 is configured to surround the outer surface of the stator core 231. The coil 233 is constructed by a wire wound around the stator core 231 via the insulating member 232.

[0031] The rotor 24 is positioned on one axial side and radially outward of the stator 23. The rotor 24 rotates relative to the stator 23 about the central axis J. The rotor 24 has a rotor yoke 241 and a magnet 242.

[0032] The rotor yoke 241 is composed of magnetic materials and is a cylindrical component with a cover on one axial side. The rotor yoke 241 is fixed to the shaft 22. The magnet 242 is cylindrical and fixed to the inner circumferential surface of the rotor yoke 241. The magnet 242 is arranged radially outward from the stator 23. On the magnetic pole surface of the inner circumferential side of the magnet 242, the N pole and S pole are arranged alternately in the circumferential direction.

[0033] The circuit board 25 is disposed on the lower side of the stator 23. The leads of the coil 233 are electrically connected to the circuit board 25. Electronic circuitry for supplying drive current to the coil 233 is mounted on the circuit board 25.

[0034] The impeller 3 is located radially inside the housing 4, axially on one side of the motor 2, and radially outside. The impeller 3 is made of resin, for example. The impeller 3 has a main body (hub) 31 and a plurality of blades 32.

[0035] The main body 31 is fixed to the rotor 24 and rotates about the central axis J extending axially. The main body 31 is a cylindrical member with a cover on one axial side. The rotor yoke 241 is fixed to the inner circumferential surface of the main body 31. A plurality of blades 32 protrude radially from the outer circumferential surface of the main body 31 and are arranged at intervals in the circumferential direction.

[0036] The housing 4 is located on the outer side of the motor 2 and the impeller 3. The housing 4 has a motor base portion 41, a cylindrical portion 42, a first rib 43, and a second rib 44.

[0037] The motor base portion 41 is disposed on the opposite side of the motor 2 along its axial direction. The motor base portion 41 has a base 411 and a bearing retaining portion 412. The base 411 is disposed on the opposite side of the stator 23 along its axial direction and is a circular plate extending radially outward about the central axis J. The bearing retaining portion 412 protrudes from a surface on one side of the base 411 toward the axial direction. The bearing retaining portion 412 is cylindrical about the central axis J. The bearing 21 is housed and held inside the bearing retaining portion 412. The stator 23 is fixed to the outer peripheral surface of the bearing retaining portion 412. Thus, the motor base portion 41 supports the stator 23.

[0038] The cylindrical portion 42 is disposed radially outward from the impeller 3. The cylindrical portion 42 extends axially. The cylindrical portion 42 is cylindrical. An air inlet 421 with a circular opening is disposed at one axial end of the cylindrical portion 42. An exhaust port 422 with a circular opening is disposed at the other axial end of the cylindrical portion 42.

[0039] The first rib 43 and the second rib 44 are positioned below the blade 32, adjacent to the exhaust port 422. The first rib 43 connects the motor base portion 41 and the cylinder portion 42. The second rib 44 is connected to the first rib 43, forming a ring shape centered on the central axis J.

[0040] In the axial flow fan 1 configured as described above, when a drive current is supplied to the coil 233 of the stator 23, a radial magnetic flux is generated in the stator core 231. The magnetic field generated by the magnetic flux of the stator 23 interacts with the magnetic field generated by the magnet 242, generating a torque in the circumferential direction of the rotor 24. This torque causes the rotor 24 and the impeller 3 to rotate about the central axis J. When the axial flow fan 1 is viewed from the axial side, the impeller 3 rotates counterclockwise. When the impeller 3 rotates, the multiple blades 32 generate airflow. In the axial flow fan 1, airflow with one axial side as the intake side and the other axial side as the exhaust side can be generated for air delivery. That is, the impeller 3 generates airflow in the axial direction by rotating the blades 32 about the central axis J.

[0041] <The composition of the impeller>

[0042] Next, the structure of impeller 3 will be explained in more detail. It should be noted that here... Figure 3 The shape of the impeller 3, as illustrated in the following figures, is similar to that used to describe the axial flow fan 1 described above. Figure 1 , Figure 2 The impeller 3 shown in the diagram has a different shape, but the impeller 3 described here can be applied to the axial flow fan 1.

[0043] Figure 3 This is a perspective view of the impeller 3 according to an exemplary embodiment of the present disclosure. Figure 4 yes Figure 3 The impeller 3 shown is a plan view viewed from the axial direction. Figure 3 and Figure 4 As shown, the impeller 3 has a plurality of blades 32 (seven in this example). The blades 32 are arranged circumferentially spaced on the outer periphery of the main body 31. The radial inner edge 321 of the blades 32 is connected to the outer peripheral surface of the main body 31. In addition, the blades 32 have a radial outer edge 322.

[0044] Here, Figure 5 It shows Figure 4 The diagram shows a partial sectional view of the section along line AA. It should be noted that... Figure 5 And later Figure 6 This is a schematic diagram for easier understanding of the embodiments of this disclosure. Specifically, a cross-sectional view of an exemplary section is shown here, comprising a central axis J and extending radially. It should be noted that... Figure 5 It shows Figure 4 A cross-sectional view of blade 32A among the multiple blades 32 shown. Furthermore, as... Figure 4 As shown, when viewed from the axial direction, the above-mentioned section intersects with the radial inner edge 321 of the blade 32A.

[0045] Furthermore, the cross-sectional features of blade 32A described below also apply to cross-sections of blade 32A other than the AA line cross-section (the cross-section including the central axis J and extending radially). Moreover, the aforementioned features also apply to blade 32 other than blade 32A.

[0046] like Figure 5 As shown, the cross-section of blade 32A is a so-called airfoil. Specifically, in the cross-section of blade 32A, the axial width W increases to a maximum axial width Wmax as it radially approaches the outer edge from the inner radial edge 321, and then decreases as it further approaches the outer radial edge 322. That is, on at least one cross-section of at least one blade 32 containing the central axis J and extending radially, the axial width first increases briefly from the inner radial edge to the outer radial edge and then decreases. Furthermore, the edge on one side of the aforementioned cross-section has a convex shape protruding towards the axial side. The apex of the convex shape is located at the position of the maximum axial width Wmax. It should be noted that the edge on the other side of the aforementioned cross-section is radially outward in a generally straight line and inclined to the other side of the axial direction. In this case, the edge on the other side of the axial direction only needs to be straight compared to the edge on the one side of the axial direction. It should be noted that the edge on the other side of the axial direction can be curved.

[0047] In the region between the radial inner edge 321 and the location near the maximum axial width Wmax on one side of the axial edge of blade 32A, the airflow forms a laminar boundary layer (flow F1). Then, in the region radially outward from the location near the maximum axial width Wmax on one side of the axial edge of blade 32A, the airflow transforms into a turbulent boundary layer and forms a turbulent boundary layer (flow F2). In the turbulent boundary layer, the flow velocity decreases to zero, and the air separates from the axial edge of blade 32A. In at least one cross-section of at least one blade 32 containing the central axis J and extending radially, the axial width first briefly increases and then decreases from the radial inner side to the radial outer side. As a result, the airflow velocity increases in the laminar boundary layer of flow F1, causing the airflow of flow F2 to move closer to the radial outer edge 322 from the separation point of the separation on one side of the axial edge of blade 32A, thereby improving the air supply efficiency. Furthermore, by generating flow F1, the intake efficiency around the main body 31 can be improved, thus improving the air supply efficiency.

[0048] In addition, such as Figure 5 As shown, the radial position Pw (the radial position of the maximum axial width Wmax) is radially inward than the radial center position Pc between the radial positions of the inner and outer edges of blade 32A. The flow F1 generates radially inward airflow, which helps increase the air intake volume in the radially inward direction (around the periphery of the main body 31). Because this effect can be produced further inward, it increases the air intake volume around the main body 31 and improves air delivery efficiency.

[0049] Figure 6 Is with Figure 5 A cross-sectional view of the same blade 32A. The chord 323 and centerline 324 are shown here. The chord 323 is a straight line connecting the radial inner edge 321 and the radial outer edge 322. The centerline 324 is the centerline of the blade 32A in a direction perpendicular to the chord 323, between one axial edge and the other axial edge. The centerline 324 warps to one axial direction, perpendicular to the chord 323. That is, the cross-section of the blade 32A has an airfoil that warps to one axial direction.

[0050] The maximum warpage point pt is the point pt on the centerline 324 where the distance L between the airfoil's centerline 324 and the airfoil's chord 323 is greatest in a direction orthogonal to the chord 323. The radial position Pm of the maximum warpage point pt is radially inward compared to the radial center position Pc between the radial positions of the inner radial edge 321 and the outer radial edge 322 of the blade 32A. The flow F1 generates radially inward airflow, which helps to increase the air intake volume in the radially inward direction (around the periphery of the main body 31). Because this effect can be produced further inward, it increases the air intake volume around the main body 31 and improves the air delivery efficiency.

[0051] Furthermore, the axial height is defined as the height along the central axis J, extending from the axial end of the cross-section of blade 32A. The axial height Hm of the maximum warp point pt is more than 50% of the axial height Ht at the radially innermost position of the chord 323. With this configuration, since this effect can be produced on a more axial side, the air intake around the main body 31 can be increased and the air delivery efficiency can be improved.

[0052] Here, for the circumferential position of the radial inner edge 321 of blade 32A, the leading edge is set to 0%, and the trailing edge to 100%. Ideally, in all sections intersecting the radial inner edge 321 within the range of 30% to 50% when viewed from the axial direction, the axial width first briefly increases and then decreases from the radial inner side to the radial outer side, and the edge on the axial side has a convex shape protruding towards the axial side. Thus, in blade 32A, the aforementioned effect of improving air delivery efficiency can be enhanced in areas where it is easy to increase. It should be noted that for blade 32A, the area corresponding to the rearward side after 50% when viewed from the axial direction has a smaller effect on air delivery efficiency and is an area where other design intentions can be prioritized. In addition, for blade 32A, the area corresponding to the forward side after 30% when viewed from the axial direction is also an area where other design intentions such as the R-shape of the leading edge can be prioritized.

[0053] <Supplementary Notes>

[0054] As described above, the impeller of this disclosure has: a main body that rotates about a central axis extending axially; and a plurality of blades that protrude radially from the outer peripheral surface of the main body and are arranged at intervals in the circumferential direction. By rotating the blades about the central axis, airflow in the axial direction is generated. In the impeller, in at least one cross section of at least one of the blades that includes the central axis and extends radially, the axial width first increases briefly from the radially inner side to the radially outer side and then decreases. The axial side is taken as the air intake side. The edge of the axial side of the cross section has a convex shape that protrudes towards the axial side. When viewed from the axial direction, the cross section intersects the radially inner edge of the blade (first configuration).

[0055] Alternatively, the configuration can be as follows: In the first configuration described above, the radial position with the largest axial width is radially inner than the radial center position between the radial position of the inner radial edge of the blade and the radial position of the outer radial edge of the blade (second configuration).

[0056] Alternatively, the following configuration can be adopted: In the first or second configuration described above, the cross section has an airfoil that warps to one side of the axial direction, and the point on the center line that has the greatest distance between the center line of the airfoil and the chord of the airfoil in a direction orthogonal to the chord is taken as the maximum warping point, and the radial position of the maximum warping point is radially inward than the radial center position between the radial position of the radial inner edge of the blade and the radial position of the radial outer edge of the blade (third configuration).

[0057] Alternatively, the following configuration can be adopted: In the third configuration described above, the height along the central axis direction from the other end of the cross section is taken as the axial height, and the axial height of the maximum warping point is more than 50% of the axial height of the innermost radial position of the chord (fourth configuration).

[0058] Alternatively, the following configuration may be adopted: In any of the first to fourth configurations described above, for the circumferential position of the radial inner edge of the blade, with the leading edge set to 0% and the trailing edge set to 100%, in all the sections intersecting the radial inner edge within a range of 30% to 50% when viewed from the axial direction, the axial width first briefly increases and then decreases from the radial inner side to the radial outer side (fifth configuration).

[0059] Furthermore, the axial flow fan disclosed herein includes: an impeller according to any one of the first to fifth configurations described above; and a motor (sixth configuration) for driving the impeller to rotate.

[0060] This disclosure can be used, for example, in axial flow fans for various applications.

[0061] Explanation of reference numerals in the attached figures: 1: Axial flow fan; 2: Motor; 3: Impeller; 4: Casing; 21: Bearing; 22: Axis; 23: Stator; 24: Rotor; 25: Circuit board; 31: Main body; 32, 32A: Blades; 41: Motor base section; 42: Cylindrical part; 43: First rib; 44: Second rib; 231: Stator core; 232: Insulating components; 233: Coil; 241: Rotor yoke; 242: Magnet; 321: Radial inner edge; 322: Radial outer edge; 323: Wing chord; 324: Center line; 411: Base; 412: Bearing retainer; 421: Air intake; 422: Exhaust port; J: Central axis.

Claims

1. An impeller, said impeller having: The main body rotates about a central axis extending axially; and Multiple blades protrude radially from the outer peripheral surface of the main body and are arranged at circumferential intervals. By rotating the blades about the central axis, an axially flowing wind is generated in the impeller. In at least one cross-section of at least one of the blades, which includes the central axis and extends radially, the axial width first increases briefly from the radially inner side to the radially outer side and then decreases. With the axial side designated as the intake side, the edge of the axial side of the cross-section has a convex shape protruding towards the axial side. When viewed from the axial direction, the cross section intersects the radial inner edge of the blade.

2. The impeller according to claim 1, wherein, The radial position with the largest axial width is radially inner than the radial center position between the radial position of the inner radial edge and the radial position of the outer radial edge of the blade.

3. The impeller according to claim 1, wherein, The cross-section has an airfoil that warps to one side of the axial direction. The point on the centerline that is furthest from the centerline of the airfoil in a direction orthogonal to the chord of the airfoil is taken as the point of maximum warp. The radial position of the maximum warping point is radially inward compared to the radial center position between the radial position of the inner radial edge of the blade and the radial position of the outer radial edge of the blade.

4. The impeller according to claim 3, wherein, The axial height is defined as the height along the central axis, starting from the other end of the cross-section along the axial direction. The axial height of the maximum warping point is more than 50% of the axial height of the innermost radial position of the chord.

5. The impeller according to claim 1, wherein, For the circumferential position of the radial inner edge of the blade, with the leading edge set to 0% and the trailing edge set to 100%, in all the sections that intersect the radial inner edge within the range of 30% to 50% when viewed from the axial direction, the axial width first increases briefly from the radial inner side to the radial outer side and then decreases, and the edge on the axial side has a convex shape that protrudes to the axial side.

6. An axial flow fan, said axial flow fan having: An impeller according to any one of claims 1 to 5; and a motor for driving the impeller to rotate.

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