This application claims priority from Japanese Patent Application No. 2016-112333 filed on Jun. 6, 2016, the entire subject matter of which is incorporated herein by reference.
This disclosure relates to an impeller and a fan including the impeller.
There is an axial fan that includes an impeller having a hub and a plurality of blades disposed on an outer periphery of the hub, and a housing surrounding the impeller. The blade has a leading edge angle (α) which is within a range of −8 degrees to −20 degrees, an attaching angle (β) which is within a range of 36 degrees to 50 degrees, and a twisting angle (θ) which is within a range of 10 degrees ±2 degrees (see JP-A-2011-247246).
It is desirable for fans to obtain high cooling performance by improving air volume-static pressure characteristic without increasing power consumption.
This disclosure is to provide an impeller capable of improving air volume-static pressure characteristic while suppressing an increase in power consumption and a fan including the impeller.
This disclosure provides an impeller includes: a hub having a ring shape; and a plurality of blades that are provided on an outer periphery of the hub, wherein the blade has a trailing edge formed such that an inner side of a radial width of the blade is curved in a direction opposite to a rotation direction, in a plan view as viewed in a direction of a rotation axis.
In the above described impeller, the blade may have a shape, of which the trailing edge swells toward a suction side.
In the above described impeller, the blade may be formed such that a chord length at an outermost side in a radial direction is longer that a chord length at a side closest to a rotation center.
In the above described impeller, in a plan view as viewed in the direction of the rotation axis, the blade may have a leading edge that is curved in the rotation direction.
In the above described impeller, in the plan view as viewed in the direction of the rotation axis, the leading edge may be formed such that an outer end of the leading edge is located closer to a side in the rotation direction than a straight line connecting the rotation center and a hub-side end of the leading edge.
In the above described impeller, in a view as viewed in a direction perpendicular to the rotation axis, the leading edge may be formed such that the outer end of the leading edge comes outward out of an end, which is the outer peripheral surface of the hub, on the leading edge.
In the above described impeller, the blade may be formed such that the outer end of the leading edge is curved toward the pressure side.
In the above described impeller, the blade may be formed such that a maximum camber at the outermost side in the radial direction of the blade and a maximum camber at a side closest to the rotation center are larger than a maximum camber at an approximate center of the radial width.
In the above described impeller, the maximum camber at the outermost side in the radial direction and the maximum camber at the side closest to the rotation center may be larger than 0.2% of a chord length, and the maximum camber at the approximate center of the radial width may be less than 0.2% of the chord length.
In the above described impeller, in the plan view as viewed in the direction of the rotation axis, two blades adjacent to each other may be formed such that a part of the leading edge of one blade overlaps with a part of the trailing edge of the other blade.
In the above described impeller, the trailing edge may be located on a plane substantially flush with the end of the hub on the trailing edge.
A fan may include the above-described impeller; and a motor configured to rotate the impeller.
The above-described fan may includes a casing, wherein the casing includes: a base portion on which the motor is disposed; a sidewall portion that is provided along the outer periphery of the blade and covers the outer periphery of the leading edge of the blade; and a connection portion that connects the sidewall portion and the base portion.
According to this disclosure, it is possible to provide an impeller capable of improving the air volume-static pressure characteristic while suppressing the increase in power consumption and the fan including the impeller.
The foregoing and additional features and characteristics of this disclosure will become more apparent from the following detailed descriptions considered with the reference to the accompanying drawings, wherein:
A aspect for carrying out (hereinafter, referred to as an “embodiment”) of this disclosure will be described in detail below with reference to the accompanying drawing
The same elements are denoted by the same reference numerals throughout the description of the embodiment.
In
As illustrated in
However, the casing 10 may be unnecessary in some cases depending on a using mode of the fan, so that the casing 10 may be omitted in these cases.
In addition, the casing 10 may be made of metal without being limited to the resin. However, since the resin is excellent in terms of mass production, the casing 10 is preferably made of the resin.
(Casing)
As illustrated in
In this embodiment, the connection portion 13 is provided in the form of spoke, but may be provided in the form of stationary blade.
As illustrated in
A stator core 21 of the motor 20 is fixed to an outer peripheral surface of the bearing housing 11a, so that a stator 20A of the motor 20 is disposed with respect to the base portion 11.
In this embodiment, the bearing housing 11a is attached to the base portion 11. However, the bearing housing 11a may be molded integrally with the base portion at the time of molding of the casing 10 in a resin molding manner such as injection molding.
(Motor)
The motor 20 mainly includes the stator 20A and the rotor 20B.
The stator 20A includes the stator core 21 fixed to the outer peripheral surface of the bearing housing 11a, an insulator 22 provided on the stator core 21, and a coil 23 provided on the stator core 21 with the insulator 22 interposed therebetween.
On the other hand, the rotor 20B includes the shaft 25 that is rotatably supported by the two bearings 14 provided in the bearing housing 11a and serves as a rotating shaft, a rotor yoke 26 that is fixed to the shaft 25 and rotates together with the shaft 25, and a rotor magnet 27 that is fixed to the rotor yoke 26 and rotates together with the shaft 25 and the rotor yoke 26.
The rotor yoke 26 includes a disk portion 26a having a press-fit fixing portion 26aa to which the shaft 25 is press-fitted at the center, and a cylindrical portion 26b, one end of which is connected to an outer peripheral portion of the disk portion 26a and which is provided such that the rotor magnet 27 faces the stator core 21 so as to cover the outer periphery of the stator core 21. The cylindrical portion 26b also serves as a portion to which the impeller 30 (to be described below) is attached.
(Impeller)
Contrary to
Arrows illustrated in
As illustrated in
As illustrated in
More specifically, as can be seen from a portion B surrounded by a dotted line in
Since an outer side of the blade 32 has a greater distance from the rotation center O of the impeller 30 in the radial direction of the blade 32, the impeller 30 has a higher circumferential speed at the time of rotation.
For this reason, a workload given by the blade 32 to the air becomes larger toward the outer side in the radial direction of the blade 32. Therefore, when the impeller is configured to receive a lot of air at the outer side in the radial direction of the blade 32, an air volume can he increased, and, at the same time, a torque to be applied to the motor 20 and power consumption also increase.
Thus, the trailing edge 32a is formed in such a manner that the inner side of the radial width W of the blade 32 is curved in the direction opposite to the rotation direction (see the arrow), whereby a side close to the trailing edge 32a of the blade 32 has the swelling shape. With such a configuration, the air taken in from the leading edge 32b of the blade 32 flows along the pressure side 33a of the blade 32 and flows to the air outlet, and thus the flow of the air is guided to the inner side of the blade 32, which is small in terms of the load related to the motor 20, rather than the outer side of the blade 32. Further, with such a configuration, the increase in torque is suppressed, and the air is efficiently delivered while suppressing the increase in power consumption.
On the other hand, a straight line connecting the leading edge 32b and the trailing edge 32a in a cross section obtained when the blade 32 is cut at a portion equidistant from the rotation center O is called a chord, and a length of the chord is called a chord length. As can be understood from the shape of the blade 32 illustrated in
As illustrated in
Further, as illustrated in
That is, the overall shape of the blade 32 is designed such that the area of the outer side in the radial direction of the blade 32 having a large volume of work becomes large and the air volume is obtained.
Further, as illustrated in
As described above, the outer side of the blade 32 has a large volume of work. However, when a strong air is received at the outer side of the blade 32, the torque related to the motor 20 increases and the power consumption increases.
Specifically, since the leading edge 32b of the blade 32 is a portion which starts to take air in, only the flow of air sucked by a suction force accompanying the flow of the air blown from the trailing edge 32a is formed, so that the leading edge 32b is a position where a collision force of air against the blade 32 is large.
Therefore, the outer end 34a of the leading edge 32b, which is considered to increase the collision force of air against the blade 32, set to have the shape laid slightly on the pressure side 33a as described above, so that a collision angle with the air is gentle, and thus the air smoothly flows (in a figurative sense, for example, slidingly flows) along the surface of the pressure side 33a rather than colliding with the pressure side 33a on the outer end 34a of the leading edge 32b.
With such a configuration, it is possible to obtain the area on the outer end 34a of the leading edge 32b in which the volume of work of the blade 32 is large, and to suppress the increase in the torque related to the motor 20 while increasing the take-in of the air.
By the way, according to this embodiment, as illustrated in
In this way, a ratio of a clearance 40, through which the air can linearly exit from the air inlet of the impeller 30 toward the air outlet, becomes smaller, the air blown out when a air outlet static pressure is high becomes difficult to be pushed back to the take-in side of the air, so that air volume-static pressure characteristic can be further improved.
Then, the description will be made with respect to results obtained when the fan 1 according to the embodiment using the impeller 30 having the blade 32 as described above is compared with a fan using an comparative impeller, in terms of the air volume-static pressure characteristic and the power consumption.
(Performance Comparison)
First, the description will be briefly made with respect to a difference in a blade between the fan (the comparative example) using the existing impeller and the fan 1 (embodiment) using the impeller 30 according to the embodiment, and then the description will be made with respect to the air volume-static pressure characteristic and the power consumption.
An upper drawing of
As illustrated in the lower drawing of
Since the lower drawing of
Further, as illustrated in the lower drawing of
A percentage of a dimension D between the chord (see the alternate long and short dash line) and the camber line CL with respect to the chord length L is called a camber C (C=“D/L”×100 (%)), and the maximum value of values of the camber C obtained depending on the chord is called a maximum camber.
An arrow illustrated in
In addition, a leading edge of a blade 132 is denoted by reference numeral 132b, and a trailing edge thereof is denoted by reference numeral 132a.
In
Meanwhile, the chord length axis is assumed to be normalized such that the chord length becomes 1.
As can be seen by comparison of
in the camber of the blade 32 according to the embodiment at the center of the radial width W, the maximum camber is slightly larger than the camber of the blade 132 according to the comparative example at the center of the radial width, but is similar to the maximum camber of the blade according to the comparative example at the outer side and is not considerably large the maximum camber. Similarly to the blade according to the comparative example, it is understood that the center of the radial width W of the blade 32 according to the embodiment has a shape approximate to the straight line without being much curved.
As illustrated in
As described above, the blade 32 of the embodiment is configured such that the air taken in from the leading edge 32b of the blade 32 flows along the pressure side 33a (see
For this reason, the center of the radial width W of the blade 32 is formed such that the maximum camber is small and resistance is hardly generated, whereas the outer side of the blade 32 is designed such that the maximum camber is large and the volume of work increases.
The reason why the camber of the blade 32 at the side closer to the hub 31 is similar to the camber of the blade at the outer side is to guide the air to the inner side of the blade 32 similarly to the outer side so that turbulence of the flow does not occur due to the collision of the air flowing on the pressure side 33a with the hub 31.
Further, as can be seen from
As described above, this means that the side close to the trailing edge 32a of the blade 32 has a swelling shape (see the portion B surrounded by the dotted line in
In the graph illustrated in
Circles indicated in the graph of
Triangles indicate results of the fan according to the comparative example, the air volume-static pressure characteristic is indicated by a solid line, and the power consumption is indicated by a dotted line.
As illustrated in
Further, it is understood that the power consumption of the fan according to the embodiment is substantially similar or slightly improved compared to that of the fan according to the comparative example without exceeding the power consumption of the fan according to the comparative example even at any air volume.
Therefore, according to the fan 1 using the impeller 30 of the embodiment, it is possible to improve the air volume-static pressure characteristic while suppressing an increase in power consumption.
While the embodiment of this disclosure has been described, various changes of this disclosure can be made without departing from the spirit.
In the above description, the case is exemplified where the maximum camber of the outermost side in the radial direction of the blade 32 and the side closest to the rotation center O exceeds 0.4%, which is approximately 0.5%, as illustrated in
However, the maximum camber of the outermost side in the radial direction of the blade 32 and the side closest to the rotation center O is preferably larger than 0.2%, and more preferably larger than 0.3%.
In the above description, the case is exemplified where the maximum camber of the blade 32 is formed at a position within 40% of the normalized long axis of the chord from the leading edge 32b even at any position of the outer side in the radial direction of the blade, the center of the radial width W, and the side closer to the hub 31, but it is not necessarily limited thereto. However, the maximum camber is preferably formed at a position within 50% of the normalized long axis of the chord from the leading edge 32b.
In the above description, the case is exemplified where an outer rotor-type motor is used as the motor 20 for rotating the impeller 30, but the motor 20 may be an inner rotor-type motor.
In addition, the sidewall portion 12 of the casing 10 provided along the outer periphery of the blade 32 covers only a part of the leading edge 32b of the blade 32 as described above, but the sidewall portion 12 may entirely cover the side surface of the blade 32. Further, the sidewall portion 12 is not limited to the ring shape (cylindrical shape) or the like, and may have a rectangular outer shape formed with a circular hole in which the impeller 30 is disposed.
In the embodiment described above, as illustrated in
While the specific embodiment of this disclosure has been described, the technical scope of this disclosure is not limited to the above described embodiment. It is apparent to persons skilled in the art that various changes may be made without departing from the spirit of this disclosure and such changes fall within the technical scope of this disclosure.
Number | Date | Country | Kind |
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2016-112333 | Jun 2016 | JP | national |
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Number | Date | Country | |
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20170350409 A1 | Dec 2017 | US |