Impeller and axial fan

Abstract

The present invention provides an impeller capable of improving airflow efficiency, and an axial flow fan having the impeller. [Solution] The impeller 3 has a body portion 31 that rotates around a central axis extending in the axial direction, and a plurality of blades 32A that protrude radially from the outer circumferential surface of the body portion and are spaced apart in the circumferential direction, and the impeller generates air that flows in the axial direction by the rotation of the blades around the central axis, and in at least one cross section extending radially including the central axis of at least one of the blades, the axial width W increases once from the radially inward to the radially outward direction and then decreases. With one axial side as the intake side, the edge on the axial side of the cross section has a convex shape that protrudes to the axial side. The cross section intersects the radially inner edge 321 of the blade when viewed in the axial direction.

Description

Technical Field

[0001] The present disclosure relates to an impeller.

Background Art

[0002] Conventionally, an impeller used for an axial fan is known. The impeller has a hub and a plurality of blades fixed to the hub (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] There has been room for improvement in the impeller as described above from the viewpoint of blowing efficiency.

[0005] An object of the present disclosure is to provide an impeller capable of improving blowing efficiency and an axial fan having the impeller.

Means for Solving the Problems

[0006] An exemplary impeller of the present disclosure has a body portion that rotates around a central axis extending in the axial direction, and a plurality of blades that project radially from the outer peripheral surface of the body portion and are arranged at intervals in the circumferential direction, and the blades generate wind flowing in the axial direction by rotating around the central axis. In at least one cross-section extending radially including the central axis in at least one of the blades, the axial width once increases and then decreases from the radially inner side toward the radially outer side. With one axial side as the intake side, the edge on one axial side in the cross-section has a convex shape protruding toward one axial side, and the cross-section intersects the radially inner edge of the blade when viewed axially. [Effects of the Invention]

[0007] According to the exemplary impeller of this disclosure, airflow efficiency can be improved. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a perspective view from above of an axial flow fan according to an exemplary embodiment of the present disclosure. [Figure 2] Figure 2 is a longitudinal cross-sectional view of an axial fan according to an exemplary embodiment of the present disclosure. [Figure 3] Figure 3 is a perspective view of an impeller according to an exemplary embodiment of the present disclosure. [Figure 4] Figure 4 is a plan view of the impeller shown in Figure 3, viewed in the axial direction. [Figure 5] Figure 5 shows a schematic partial cross-sectional view based on the section of line AA shown in Figure 4. [Figure 6] Figure 6 is a cross-sectional view similar to that of Figure 5. [Modes for carrying out the invention]

[0009] Exemplary embodiments of this disclosure are described below with reference to the drawings.

[0010] In this specification, in the axial flow fan 1, the direction parallel to the central axis J of the impeller 3, which will be described later, is referred to as the "axial direction." Of the axial directions, the intake side is referred to as "axial side Da," and the exhaust side is referred to as "axial side Db." The direction perpendicular to the central axis J is referred to as the "radial direction." Of the radial directions, the direction approaching the central axis J is referred to as the "radial inward direction," and the direction moving away from the central axis J is referred to as the "radial outward direction." The direction of rotation around the central axis J is referred to as the "circumferential direction Dc."

[0011] These are used solely for explanatory purposes and are not intended to limit the actual location, direction, or name of any particular place.

[0012] <Configuration of an axial fan> FIG. 1 is a perspective view of the axial flow fan 1 according to an exemplary embodiment of the present disclosure as viewed from above. FIG. 2 is a longitudinal sectional view of the axial flow fan 1 according to an exemplary embodiment of the present disclosure.

[0013] The axial flow fan 1 has a motor 2, an impeller 3, and a housing 4.

[0014] The motor 2 is disposed radially inward of the housing 4. The motor 2 is supported by a motor base portion 41 of the housing 4. The motor 2 rotates the impeller 3 about a central axis J extending in the axial direction. That is, the axial flow fan 1 has an impeller 3 and a motor 2 that rotationally drives the impeller 3.

[0015] 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.

[0016] The bearing 21 is held inside a cylindrical bearing holding portion 412 in the motor base portion 41. The bearing 21 is constituted by a sleeve bearing. Note that the bearing 21 may be constituted by a pair of ball bearings arranged vertically.

[0017] The shaft 22 is arranged along the central axis J. The shaft 22 is a columnar member made of a metal such as stainless steel and extending in the axial direction. The shaft 22 is rotatably supported about the central axis J by the bearing 21.

[0018] The stator 23 is fixed to the outer peripheral surface of the bearing holding portion 412 of the motor base portion 41. The stator 23 has a stator core 231, an insulator 232, and a coil 233.

[0019] The stator core 231 is formed by laminating electromagnetic steel sheets such as silicon steel sheets in the vertical direction. The insulator 232 is made of an insulating resin. The insulator 232 is provided to surround the outer surface of the stator core 231. The coil 233 is composed of a conducting wire wound around the stator core 231 via the insulator 232.

[0020] The rotor 24 is arranged on one axial side and radially outward of the stator 23. The rotor 24 rotates around the central axis J with respect to the stator 23. The rotor 24 has a rotor yoke 241 and a magnet 242.

[0021] The rotor yoke 241 is made of a magnetic material and is a cylindrical member having a lid on one axial side. The rotor yoke 241 is fixed to the shaft 22. The magnet 242 is cylindrical and is fixed to the inner peripheral surface of the rotor yoke 241. The magnet 242 is arranged radially outward of the stator 23. N poles and S poles are alternately arranged in the circumferential direction on the magnetic pole surface on the inner peripheral side of the magnet 242.

[0022] The circuit board 25 is arranged below the stator 23. The lead wire of the coil 233 is electrically connected to the circuit board 25. An electronic circuit for supplying a drive current to the coil 233 is mounted on the circuit board 25.

[0023] The impeller 3 is arranged radially inward of the housing 4 and on one axial side and radially outward of the motor 2. The impeller 3 is made of, for example, resin. The impeller 3 has a body (hub) 31 and a plurality of blades 32.

[0024] The body 31 is fixed to the rotor 24 and rotates around the central axis J extending in the axial direction. The body 31 is a cylindrical member having a lid on one axial side. The rotor yoke 241 is fixed to the inner peripheral surface of the body 31. The plurality of blades 32 project radially from the outer peripheral surface of the body 31 and are arranged at intervals in the circumferential direction.

[0025] The housing 4 is positioned outside the motor 2 and impeller 3. The housing 4 has a motor base portion 41, a cylindrical portion 42, a first rib 43, and a second rib 44.

[0026] The motor base portion 41 is positioned on the other axial side of the motor 2. The motor base portion 41 has a base portion 411 and a bearing holder portion 412. The base portion 411 is positioned on the other axial side of the stator 23 and is disc-shaped, expanding radially around the central axis J. The bearing holder portion 412 protrudes from one axial side surface of the base portion 411 toward the other axial side. The bearing holder portion 412 is cylindrical around the central axis J. The bearing 21 is housed and held inside the bearing holder portion 412. The stator 23 is fixed to the outer circumferential surface of the bearing holder portion 412. In this way, the motor base portion 41 supports the stator 23.

[0027] The cylindrical portion 42 is positioned radially outward from the impeller 3. The cylindrical portion 42 extends in the axial direction. The cylindrical portion 42 is cylindrical in shape. An intake port 421, which is a circular opening, is positioned at one axial end of the cylindrical portion 42. An exhaust port 422, which is a circular opening, is positioned at the other axial end of the cylindrical portion 42.

[0028] The first rib 43 and the second rib 44 are positioned below the blade 32 and adjacent to the exhaust port 422. The first rib 43 connects the motor base section 41 and the cylindrical section 42. The second rib 44 is connected to the first rib 43 and is annular in shape with respect to the central axis J.

[0029] In the axial flow fan 1 with the above configuration, 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 and the magnetic field generated by the magnet 242 act together, generating torque in the circumferential direction of the rotor 24. This torque causes the rotor 24 and the impeller 3 to rotate around the central axis J. The impeller 3 rotates counterclockwise when viewed from one axial side of the axial flow fan 1. As the impeller 3 rotates, airflow is generated by the multiple blades 32. In the axial flow fan 1, airflow can be generated with one axial side as the intake side and the other axial side as the exhaust side, thereby providing airflow. That is, the impeller 3 generates airflow that flows axially as the blades 32 rotate around the central axis J.

[0030] <Impeller configuration> Next, the configuration of the impeller 3 will be explained in more detail. Note that the shape of the impeller 3, which will be illustrated and explained in detail from Figure 3 onward, is different from the shape of the impeller 3 illustrated in Figures 1 and 2, which were used to explain the axial flow fan 1 mentioned earlier. However, it is possible to apply the impeller 3 described here to the axial flow fan 1.

[0031] Figure 3 is a perspective view of an impeller 3 according to an exemplary embodiment of the present disclosure. Figure 4 is a plan view of the impeller 3 shown in Figure 3, viewed in the axial direction. As shown in Figures 3 and 4, the impeller 3 is provided with a plurality of blades 32 (here, as an example, seven blades). The blades 32 are arranged at circumferential intervals on the outer circumference of the body 31. The radial inner edge 321 of each blade 32 is connected to the outer circumferential surface of the body 31. The blades 32 also have a radial outer edge 322.

[0032] Here, Figure 5 shows a partial cross-sectional view taken along line AA shown in Figure 4. Figures 5 and 6, described later, are schematic diagrams intended to facilitate understanding of the embodiments of this disclosure. Specifically, here, a cross-sectional view is shown taken from one exemplary cross-section extending radially including the central axis J. Figure 5 shows a cross-sectional view of blade 32A, one of the multiple blades 32 shown in Figure 4. Furthermore, as shown in Figure 4, the above cross-section intersects the radial inner edge 321 of blade 32A when viewed in the axial direction.

[0033] Furthermore, the characteristics of the cross-section of blade 32A described below also hold true in a cross-section other than the AA line cross-section of blade 32A (a cross-section extending radially including the central axis J). Moreover, the above characteristics also hold true for blade 32, which is separate from blade 32A.

[0034] As shown in Figure 5, the cross-section of the blade 32A is a so-called airfoil. Specifically, in the cross-section of the blade 32A, the axial width W increases from the radial inner edge 321 toward the radial outer edge 322 to the maximum axial width Wmax, and then decreases further toward the radial outer edge 322. That is, in at least one cross-section extending radially including the central axis J of at least one blade 32, the axial width increases once from the radial inner to the radial outer edge before decreasing. Furthermore, one edge on the axial side of the above cross-section has a convex shape that protrudes toward the axial side. The apex of the convex shape is located at the position of the maximum axial width Wmax, where the axial width is at its maximum. The other edge on the axial side of the above cross-section is inclined radially outward and toward the other axial side in a nearly straight line. In this case, the other edge on the axial side only needs to be straighter than the edge on the axial side. The other edge on the axial side may also be curved.

[0035] In the region between the radial inner edge 321 and the position of the maximum axial width Wmax on one axial side edge of the blade 32A, the airflow becomes a laminar boundary layer (flow F1). Then, in the region radially outward from the position of the maximum axial width Wmax on one axial side edge of the blade 32A, the airflow transitions to a turbulent boundary layer, and a turbulent boundary layer is formed (flow F2). In the turbulent boundary layer, the flow velocity decreases to zero, and the air separates from the axial side edge of the blade 32A. In at least one cross section extending radially including the central axis J of at least one blade 32, the axial width increases and then decreases from the radially inward to the radially outward direction. This increases the airflow velocity in the laminar boundary layer of flow F1, bringing the separation point where the air of flow F2 separates from the axial side edge of the blade 32A closer to the radially outer edge 322, thereby improving the airflow efficiency. Furthermore, the generation of flow F1 improves the intake efficiency around the body 31, thereby improving the airflow efficiency.

[0036] Furthermore, as shown in Figure 5, the radial position Pw where the axial width is maximum (the radial position of the maximum axial width Wmax) is radially inward from the radial center position Pc between the radial position of the radial inner edge of the blade 32A and the radial position of the radial outer edge of the blade 32A. The flow F1 generates a radially inward airflow, contributing to an increase in the intake volume radially inward (around the body 31), but since this effect can be generated more radially inward, it becomes possible to increase the intake volume around the body 31 and improve the airflow efficiency.

[0037] Figure 6 is a cross-sectional view of the same blade 32A as in Figure 5. Here, the chord 323 and centerline 324 are shown. 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 between one axial side edge and the other axial side edge, perpendicular to the chord 323. The centerline 324 is perpendicular to the chord 323 and curves in one axial direction. That is, the cross-section of the blade 32A has an airfoil shape that curves in one axial direction.

[0038] The point of maximum curvature pt is the point pt on the centerline 324 where the distance L in the direction perpendicular to the chord 323 between the centerline 324 and the chord 323 of the airfoil is maximum. The radial position Pm of the point of maximum curvature pt is radially inward from the radial center position Pc between the radial position of the radial inner edge 321 of the blade 32A and the radial position of the radial outer edge 322 of the blade 32A. The flow F1 generates a radially inward airflow, contributing to an increase in intake air volume radially inward (around the fuselage 31), but by generating this effect further radially inward, it becomes possible to increase the intake air volume around the fuselage 31 and improve the airflow efficiency.

[0039] Furthermore, the axial height is defined as the height along the central axis J from the other axial end of the cross-section of the blade 32A. The axial height Hm of the point of maximum curvature pt is 50% or more of the axial height Ht of the position furthest radially inward on the chord 323. With this configuration, the above-mentioned effects can be produced more on one axial side, thereby increasing the intake volume around the fuselage 31 and improving the airflow efficiency.

[0040] Here, the leading edge is set to 0% and the trailing edge to 100% for the circumferential position of the radial inner edge 321 of the blade 32A. In this case, it is desirable that in all cross-sections intersecting the radial inner edge 321 in the range of 30% to 50% when viewed in the axial direction, the axial width increases once from the radially inward to the radially outward direction, then decreases, and that the edge on one side of the axial direction has a convex shape that protrudes to the axial side. This makes it possible to greatly increase the effect of improving the airflow efficiency of the blade 32A in the region where it is easy to greatly increase the effect described above. Note that in the region of the blade 32A corresponding to the area behind 50% when viewed in the axial direction, the effect of improving airflow efficiency is small, and it is a region where other design intentions may be prioritized. Also, in the region of the blade 32A corresponding to the area in front of 30% when viewed in the axial direction, it is a region where other design intentions, such as the R shape of the leading edge, may be prioritized.

[0041] <Note> As described above, the impeller of the present disclosure has a body that rotates around a central axis extending in the axial direction, and a plurality of blades that project radially from the outer circumferential surface of the body and are spaced apart in the circumferential direction, and the impeller generates an axially flowing air by the rotation of the blades around the central axis, wherein in at least one cross section extending radially including the central axis of at least one of the blades, the axial width increases once from the radially inward to the radially outward direction and then decreases, with one axial side being the intake side, the edge on one axial side of the cross section has a convex shape projecting to the axial side, and the cross section intersects the radially inner edge of the blade when viewed in the axial direction (first configuration).

[0042] Furthermore, in the first configuration described above, the radial position where the axial width is maximum may be radially inward from 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 (second configuration).

[0043] Furthermore, in the first or second configuration described above, the cross section may have an airfoil shape that curves to one side in the axial direction, and the point on the center line where the distance between the center line of the airfoil and the chord of the airfoil is maximum in the direction perpendicular to the chord is defined as the point of maximum curvature, and the radial position of the point of maximum curvature is radially inward from 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).

[0044] Furthermore, in the third configuration described above, the axial height may be defined as the height in the direction along the central axis from the other axial end of the cross section, and the axial height of the point of maximum curvature may be 50% or more of the axial height of the position furthest radially inward on the chord (fourth configuration).

[0045] Furthermore, in any of the first to fourth configurations described above, with respect to the circumferential position of the radial inner edge of the blade, if the leading edge is set to 0% and the trailing edge to 100%, then in all the cross-sections that intersect the radial inner edge in the range of 30% to 50% when viewed in the axial direction, the axial width may increase once from the radially inward to the radially outward direction before decreasing (fifth configuration).

[0046] Furthermore, the axial flow fan of this disclosure comprises an impeller having one of the first to fifth configurations described above, and a motor that rotates the impeller (sixth configuration). [Industrial applicability]

[0047] This disclosure can be used, for example, in axial flow fans for various applications. [Explanation of symbols]

[0048] 1 Axial flow fan 2 motors 3 Impellers 4 Housing 21 Bearings 22 shafts 23 Status 24 rotors 25 Circuit boards 31 Torso 32, 32A blades 41 Motor base section 42 Cylinder part 43. First Rib 44. Second Rib 231 Stator Core 232 Insulators 233 coils 241 Rotor yoke 242 Magnets 321 Radial inner edge 322 Radial outer edge 323 chord 324 Center line 411 Base 412 Bearing retaining section 421 Air intake 422 Exhaust port J central axis

Claims

1. A body that rotates around a central axis extending in the axial direction, The body has a plurality of blades that protrude radially from the outer surface of the body and are spaced apart in the circumferential direction, An impeller that generates wind flowing in the axial direction by the rotation of the blades around the central axis, In at least one cross-section extending radially including the central axis in at least one of the blades, the axial width increases and then decreases from the radially inward to the radially outward direction. With one axial side being the intake side, the edge on the axial side of the cross-section has a convex shape that protrudes in the axial direction. The cross-section is an impeller that intersects with the radial inner edge of the blade when viewed in the axial direction.

2. The impeller according to claim 1, wherein the radial position at which the axial width is maximum is radially inward from 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.

3. The cross-section has an airfoil shape that curves to one side in the axial direction. The point on the center line of the airfoil where the distance between the center line of the airfoil and the chord of the airfoil is maximum in the direction perpendicular to the chord is defined as the point of maximum curvature. The impeller according to claim 1, wherein the radial position of the point of maximum curvature is radially inward from 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.

4. The height in the direction along the central axis from the other axial end of the cross-section is defined as the axial height. The impeller according to claim 3, wherein the axial height of the point of maximum curvature is 50% or more of the axial height of the position most radially inward on the chord.

5. The impeller according to claim 1, wherein, with respect to the circumferential position of the radial inner edge of the blade, with the leading edge set to 0% and the trailing edge to 100%, in all cross-sections intersecting the radial inner edge in the range of 30% to 50% when viewed in the axial direction, the axial width increases once from the radially inward to the radially outward direction, then decreases, and the edge on one side in the axial direction has a convex shape that protrudes to the axial side.

6. An axial flow fan comprising an impeller according to any one of claims 1 to 5, and a motor for rotating the impeller.

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