IMPELLER AND AXIAL FAN

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority under 35 U.S.C. § 119 to Japanese Patent Application No. 2024-231817, filed on Dec. 27, 2024, the entire contents of which are hereby incorporated herein by reference.

1. FIELD OF THE INVENTION

The present disclosure relates to impellers.

2. BACKGROUND

Conventionally, an impeller used in an axial fan is known. The impeller includes a hub and a plurality of blades fixed to the hub.

The impeller as described above has room for improvement in terms of an air blowing efficiency.

SUMMARY

An example embodiment of an impeller of the present disclosure includes a body portion to rotate about a center axis extending in an axial direction, and blades that protrude in a radial direction from an outer circumferential surface of the body portion and are located at intervals in a circumferential direction. The impeller is configured to generate a wind flowing in the axial direction due to the blades rotating around the center axis. In at least one cross section of at least one of the blades, including the center axis and extending in the radial direction, a width in the axial direction increases and then decreases from a radially inner side toward a radially outer side. An edge on one side in the axial direction in the cross section has a convex shape protruding to the one side in the axial direction with the one side in the axial direction as an intake side. The cross section intersects a radially inner edge of the at least one of the blades when viewed in the axial direction.

The above and other elements, features, steps, characteristics and advantages of the present disclosure will become more apparent from the following detailed description of the example embodiments with reference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an axial fan according to an example embodiment of the present disclosure when viewed from above.

FIG. 2 is a longitudinal cross-sectional view of an axial fan according to an example embodiment of the present disclosure.

FIG. 3 is a perspective view of an impeller according to an example embodiment of the present disclosure.

FIG. 4 is a plan view of the impeller illustrated in FIG. 3 when viewed in an axial direction.

FIG. 5 is a schematic partial cross-sectional view taken along line A-A in FIG. 4.

FIG. 6 is a cross-sectional view similar to FIG. 5.

DETAILED DESCRIPTION

Example embodiments of the present disclosure will be described below with reference to the drawings.

In the present specification, in an axial fan 1, a direction parallel to a center axis J of an impeller 3 described later is referred to as an “axial direction”. In the axial direction, an intake side is referred to as “one side in the axial direction Da”, and an exhaust side is referred to as “the other side in the axial direction Db”. A direction orthogonal to the center axis J is referred to as a “radial direction”. In the radial direction, a direction approaching the center axis J is referred to as a “radially inner side” and a direction away from the center axis J is referred to as a “radially outer side”. A rotation direction with the center axis J as a center is referred to as a “circumferential direction Dc”.

Note that these terms are merely used for description and are not intended to limit actual positional relationships, directions, names, and the like.

FIG. 1 is a perspective view of the axial fan 1 according to an example embodiment of the present disclosure when viewed from above. FIG. 2 is a longitudinal cross-sectional view of the axial fan 1 according to the example embodiment of the present disclosure.

The axial fan 1 includes a motor 2, the impeller 3, and a housing 4.

The motor 2 is disposed at the radially inner side 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 the center axis J extending in the axial direction. That is, the axial fan 1 includes the impeller 3 and the motor 2 that rotationally drives the impeller 3.

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

The bearing 21 is held inside a bearing holding portion 412 having a cylindrical shape in the motor base portion 41. The bearing 21 is formed of a sleeve bearing. The bearing 21 may be formed of a pair of ball bearings disposed vertically.

The shaft 22 is arranged along the center axis J. The shaft 22 is made of a metal such as stainless steel and is a columnar member extending in the axial direction. The shaft 22 is supported by the bearing 21 so as to be rotatable about the center axis J.

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

The stator core 231 is formed by vertically stacking electromagnetic steel plates such as silicon steel plates. The insulator 232 is made of a resin having insulating properties. The insulator 232 is provided to surround an outer surface of the stator core 231. The coil 233 is formed of a conductive wire wound around the stator core 231, with the insulator 232 interposed therebetween.

The rotor 24 is disposed on the one side in the axial direction and at the radially outer side of the stator 23. The rotor 24 rotates about the center axis J with respect to the stator 23. The rotor 24 includes a rotor yoke 241 and a magnet 242.

The rotor yoke 241 is constituted by a magnetic body and is a cylindrical member including a lid on the one side in the axial direction. The rotor yoke 241 is fixed to the shaft 22. The magnet 242 has a cylindrical shape and is fixed to an inner circumferential surface of the rotor yoke 241. The magnet 242 is disposed at the radially outer side of the stator 23. On a magnetic pole surface on an inner circumferential side of the magnet 242, N poles and S poles are alternately arranged in the circumferential direction.

The circuit board 25 is disposed below the stator 23. A lead wire of the coil 233 is electrically connected to the circuit board 25. An electronic circuit used for supplying a drive current to the coil 233 is mounted on the circuit board 25.

The impeller 3 is disposed at the radially inner side of the housing 4 and on the one side in the axial direction and at the radially outer side of the motor 2. The impeller 3 is made of, for example, a resin. The impeller 3 includes a body portion (hub) 31 and a plurality of blades 32.

The body portion 31 is fixed to the rotor 24 and rotates about the center axis J extending in the axial direction. The body portion 31 is a cylindrical member including a lid on the one side in the axial direction. The rotor yoke 241 is fixed to the inner circumferential surface of the body portion 31. The plurality of blades 32 protrude in a radial direction from an outer circumferential surface of the body portion 31 and are arranged at intervals in the circumferential direction.

The housing 4 is disposed outside the motor 2 and the impeller 3. The housing 4 includes the motor base portion 41, a tubular portion 42, a first rib 43, and a second rib 44.

The motor base portion 41 is disposed on the other side in the axial direction of the motor 2. The motor base portion 41 includes a base portion 411 and a bearing holding portion 412. The base portion 411 is disposed on the other side in the axial direction of the stator 23 and has a disk shape extending in the radial direction with the center axis J as a center. The bearing holding portion 412 protrudes from a surface of the base portion 411 on the one side in the axial direction toward the one side in the axial direction. The bearing holding portion 412 has a cylindrical shape with the center axis J as a center. The bearing 21 is accommodated and held inside the bearing holding portion 412. The stator 23 is fixed to an outer circumferential surface of the bearing holding portion 412. Thus, the motor base portion 41 supports the stator 23.

The tubular portion 42 is disposed at the radially outer side of the impeller 3. The tubular portion 42 extends in the axial direction. The tubular portion 42 has a cylindrical shape. An intake port 421 that is an opening having a circular shape is disposed at an end on the one side in the axial direction of the tubular portion 42. An exhaust port 422 that is a circular opening is disposed at an end on the other side in the axial direction of the tubular portion 42.

The first rib 43 and the second rib 44 are disposed below the blade 32 and adjacent to the exhaust port 422. The first rib 43 connects the motor base portion 41 and the tubular portion 42 to each other. The second rib 44 is connected to the first rib 43 and has an annular shape with the center axis J as a center.

In the axial fan 1 configured as described above, when a drive current is supplied to the coil 233 of the stator 23, a magnetic flux in the radial direction is generated in the stator core 231. A magnetic field generated by the magnetic flux in the stator 23 and a magnetic field generated by the magnet 242 interact with each other to generate torque in a circumferential direction of the rotor 24. The torque causes the rotor 24 and the impeller 3 to rotate with the center axis J as a center. The impeller 3 rotates counterclockwise when the axial fan 1 is viewed from the one side in the axial direction. When the impeller 3 rotate, an air flow is generated by the plurality of blades 32. The axial fan 1 can blow air by generating an air flow with the one side in the axial direction as the intake side and the other side in the axial direction as the exhaust side. That is, when the blades 32 rotate about the center axis J, the impeller 3 generates a wind flowing in the axial direction.

Next, a configuration of the impeller 3 will be described in more detail. Although the shape of the impeller 3, a specific example of which is illustrated in FIG. 3 and the subsequent drawings, is different from the shape of the impeller 3 illustrated in FIGS. 1 and 2 for describing the axial fan 1 described above, the impeller 3 described here can be applied to the axial fan 1.

FIG. 3 is a perspective view of the impeller 3 according to the example embodiment of the present disclosure. FIG. 4 is a plan view, viewed in the axial direction, of the impeller 3 illustrated in FIG. 3 As illustrated in FIGS. 3 and 4, the impeller 3 includes the plurality of (here, seven, for example) blades 32. The blades 32 are arranged at intervals in a circumferential direction on an outer circumferential side of the body portion 31. A radially inner edge 321 of the blade 32 is connected to the outer circumferential surface of the body portion 31. The blade 32 has a radially outer edge 322.

Here, FIG. 5 is a partial cross-sectional view taken along line A-A illustrated in FIG. 4. Note that FIG. 5 and FIG. 6 described later are schematic views for facilitating understanding of the embodiment according to the present disclosure. That is, here, a cross-sectional view of one exemplary cross section, among cross sections including the center axis J and extending in the radial direction, is illustrated. FIG. 5 illustrates a cross-sectional view of a blade 32A among the plurality of blades 32 illustrated in FIG. 4. As illustrated in FIG. 4, the cross section intersects the radially inner edge 321 of the blade 32A when viewed in the axial direction.

Features of the blade 32A in the cross section described below also apply to a cross section (a cross section including the center axis J and extending in the radial direction) other than the cross section of the blade 32A taken along the line A-A. The above features also apply to blades 32 other than the blade 32A.

As illustrated in FIG. 5, the cross section of the blade 32A is a so-called airfoil shape. Specifically, in the cross section of the blade 32A, a width in the axial direction W increases to a maximum width in the axial direction Wmax from the radially inner edge 321 toward the radially outer side, and then decreases toward the radially outer side up to the radially outer edge 322. That is, in at least one cross section of at least one blade 32, including the center axis J and extending in the radial direction, the width in the axial direction once increases and then decreases from the radially inner side toward the radially outer side. In addition, the edge on the one side in the axial direction in the cross section has a convex shape protruding to the one side in the axial direction. An apex of the convex shape is located at a position of the maximum width in the axial direction Wmax at which the width in the axial direction is maximized. The edge on the other side in the axial direction in the cross section is inclined substantially linearly toward the radially outer side and the other side in the axial direction. At this time, the edge on the other side in the axial direction may be linear as compared with the edge on the one side in the axial direction. The edge on the other side in the axial direction may be curved.

In a region from the radially inner edge 321 at an edge on the one side in the axial direction of the blade 32A to the vicinity of the position of the maximum width in the axial direction Wmax, the flow of the wind is a laminar boundary layer (flow F1). In a region that is radially outer side of the vicinity of the position of the maximum width in the axial direction Wmax at the edge on the one side in the axial direction of the blade 32A, the flow of the wind transitions to a turbulent boundary layer, and the turbulent boundary layer is formed (flow F2). A flow velocity decreases to zero in the turbulent boundary layer, and the wind separates from the edge on the one side in the axial direction of the blade 32A. In at least one cross section of at least one blade 32, including the center axis J and extending in the radial direction, the width in the axial direction once increases and then decreases from the radially inner side toward the radially outer side, so that the flow velocity of the wind increases in the laminar boundary layer of the flow F1, and a separation point at which the wind of the flow F2 separates from the edge on the one side in the axial direction of the blade 32A is brought closer to the radially outer edge 322, and the air blowing efficiency can be improved. Further, the generation of the flow F1 improves an air intake efficiency around the body portion 31, so that the air blowing efficiency can be improved.

As illustrated in FIG. 5, a radial position Pw (a radial position of the maximum width in the axial direction Wmax) at which the width in the axial direction is maximized is at the radially inner side of a radially central position Pc between a radial position of the radially inner edge of the blade 32A and a radial position of the radially outer edge of the blade 32A. The flow F1 generates the flow of the wind at the radially inner side, and contributes to an increase in an amount of air intake at the radially inner side (around the body portion 31). Since such an effect can be produced further at the radially inner side, it is possible to increase the amount of air intake around the body portion 31 and improve the air blowing efficiency.

FIG. 6 is a cross-sectional view of the blade 32A similar to FIG. 5. Here, a chord 323 and a center line 324 are illustrated. The chord 323 is a straight line connecting the radially inner edge 321 and the radially outer edge 322 to each other. The center line 324 is a center line in a direction perpendicular to the chord 323 between the edge on the one side in the axial direction and the edge on the other side in the axial direction of the blade 32A. The center line 324 is warped perpendicular to the chord 323 and toward the one side in the axial direction. That is, the cross section of the blade 32A has the airfoil shape that is warped toward the one side in the axial direction.

A maximum warpage point pt is the point pt on the center line 324 where a distance L between the center line 324 of the airfoil shape and the chord 323 of the airfoil shape in a direction orthogonal to the chord 323 is maximized. A radial position Pm of the maximum warpage point pt is at the radially inner side of the radially central position Pc between the radial position of the radially inner edge 321 of the blade 32A and the radial position of the radially outer edge 322 of the blade 32A. The flow F1 generates the flow of the wind at the radially inner side, and contributes to an increase in an amount of air intake at the radially inner side (around the body portion 31). Since such an effect can be produced further at the radially inner side, it is possible to increase the amount of air intake around the body portion 31 and improve the air blowing efficiency.

A height in a direction along the center axis J from the end on the other side in the axial direction in the cross section of the blade 32A is defined as a height in the axial direction. A height in the axial direction Hm of the maximum warpage point pt is 50% or more of a height in the axial direction Ht at the radially innermost position in the chord 323. With such a configuration, the above-described effect can be produced further on the one side in the axial direction, and thus it is possible to increase the amount of air intake around the body portion 31 and improve the air blowing efficiency.

Here, a circumferential position of the radially inner edge 321 of the blade 32A is defined as 0% at a leading edge and 100% at a trailing edge. In this case, it is desirable that, in all cross sections intersecting the radially inner edge 321 in a range from 30% to 50% when viewed in the axial direction, the width in the axial direction once increases and then decreases from the radially inner side toward the radially outer side, and the edge on the one side in the axial direction has the convex shape protruding to the one side in the axial direction. Thus, in the region where the effect of improving the air blowing efficiency described above is likely to be increased in the blade 32A, the efficiency can be increased. A region corresponding to a rear side of 50% in the blade 32A when viewed in the axial direction is a region where the effect of the air blowing efficiency is small and other design intentions may be prioritized. Further, a region corresponding to a front side of 30% in the blade 32A when viewed in the axial direction is also a region where other design intentions such as an R shape at the leading edge may be prioritized.

As described above, an impeller of the present disclosure includes a body portion to rotate about a center axis extending in an axial direction, and a plurality of blades that protrude in a radial direction from an outer circumferential surface of the body portion and are located at intervals in a circumferential direction. The impeller is configured to generate a wind flowing in the axial direction due to the blades rotating around the center axis. In at least one cross section of at least one of the blades, including the center axis and extending in the radial direction, a width in the axial direction increases and then decreases from radially inner toward radially outer side. An edge on one side in the axial direction in the cross section has a convex shape protruding to the one side in the axial direction with the one side in the axial direction as an intake side. The cross section intersects a radially inner edge of the at least one of the blades when viewed in the axial direction (first configuration).

In the first configuration, a configuration may be such that a radial position at which the width in the axial direction is maximized is at a radially inner side of a radially central position between a radial position of a radially inner edge of the at least one of the blades and a radial position of a radially outer edge of the at least one of the blades (second configuration).

In the first or second configuration, a configuration may be such that the cross section has an airfoil shape that is warped toward one side in the axial direction, a point on a center line where a distance between the center line of the airfoil shape and a chord of the airfoil shape in a direction orthogonal to the chord is maximized is defined as a maximum warpage point, and a radial position of the maximum warpage point is at a radially inner side of a radially central position between a radial position of a radially inner edge of the at least one of the blades and a radial position of a radially outer edge of the at least one of the blades (third configuration).

In the third configuration, a configuration may be such that, when a height in a direction along the center axis from the end on another side in the axial direction in the cross section is defined as a height in the axial direction, a height in the axial direction of the maximum warpage point is about 50% or more of a height in the axial direction of a radially innermost position in the chord (fourth configuration).

In any one of the first to fourth configurations, a configuration may be such that in a case where a circumferential position of a radially inner edge of the at least one of the blades is defined as 0% at a leading edge and 100% at a trailing edge, in all cross sections intersecting the radially inner edge in a range from about 30% to about 50% when viewed in the axial direction, the width in the axial direction once increases and then decreases from the radially inner side toward the radially outer side (fifth configuration).

An axial fan according to an example embodiment of the present disclosure includes the impeller according to any one of the above-described first to fifth configurations, and a motor that rotationally drives the impeller (sixth configuration).

Example embodiments of the present disclosure can be used, for example, in axial fans for various applications.

Features of the above-described example embodiments and the modifications thereof may be combined appropriately as long as no conflict arises.

While example embodiments of the present disclosure have been described above, it is to be understood that variations and modifications will be apparent to those skilled in the art without departing from the scope and spirit of the present disclosure. The scope of the present disclosure, therefore, is to be determined solely by the following claims.