JP2019019759A - Centrifugal fan impeller and centrifugal fan with centrifugal fan impeller - Google Patents

Abstract

To improve characteristics of a centrifugal fan by enlarging the surface area of blades while maintaining the size in a direction parallel to a rotation axis.SOLUTION: A centrifugal fan impeller 100 of the present disclosure comprises a ring 12, a back plate 14, and a plurality of fan blades 20 arranged around a rotation axis 10 between the ring 12 and the back plate 14. Each fan blade 20 has a radially-inner leading edge, a radially-outer rear edge, a first end coupled to the ring, a second end coupled to the back plate, and a front surface and a rear surface each of which is sectioned by the leading edge, the rear edge, the first end and the second end. Each of the front surface and the rear surface has a convex surface area in which curvature in the direction of the rotation axis 10 is positive, and a concave area in which curvature in the direction of the rotation axis is negative, and the convex surface area and the concave surface area are coupled to each other along the direction of the rotation axis.SELECTED DRAWING: Figure 1

Description

  The present application relates to a centrifugal fan impeller and a centrifugal fan including the centrifugal fan impeller.

  A centrifugal fan is a blower that causes air or other gas to flow radially outward by a plurality of blades that rotate about an axis.

  Japanese Patent Application Laid-Open No. 2002-349486 discloses a centrifugal blower characterized by the shape of a blade viewed from the direction of a rotating shaft.

  JP-T-2006-535194 discloses a centrifugal blower in which the trailing edge of the blade is curved in an S shape.

JP 2002-349486 A JP-T-2006-535194

  Embodiments of the present disclosure provide a centrifugal fan impeller with improved pressure-up performance and a centrifugal fan including the impeller.

  In an exemplary embodiment, the centrifugal fan impeller of the present disclosure is a centrifugal fan impeller having a rotation axis, and is arranged around the rotation axis between a ring, a back plate, and the ring and the back plate. A plurality of fan blades. Each of the plurality of fan blades includes a radially inner front edge, a radially outer rear edge, a first end connected to the ring, and a second end connected to the back plate, Each has a front surface and a back surface defined by the front edge, the rear edge, the first end, and the second end. Each of the front surface and the back surface has a convex surface region having a positive curvature in the direction of the rotation axis and a concave surface region having a negative curvature in the direction of the rotation axis. The convex surface region and the concave surface region are connected along the direction of the rotation axis.

  In an exemplary embodiment, the centrifugal fan of the present disclosure includes a motor, a centrifugal fan impeller coupled to the motor, and a casing that houses the centrifugal fan impeller, and the centrifugal fan impeller includes the centrifugal fan described above. Impeller.

  According to the embodiment of the present disclosure, it is possible to increase the surface area of the blade while maintaining the size in the direction parallel to the rotation axis, thereby improving the characteristics of the centrifugal fan impeller.

FIG. 1 is a perspective view of a centrifugal fan impeller in an embodiment of the present disclosure. FIG. 2 is a perspective view illustrating a part of the centrifugal fan impeller in the embodiment of the present disclosure. FIG. 3 is a schematic diagram illustrating a cross-sectional configuration of the centrifugal fan impeller in the embodiment of the present disclosure. FIG. 4 is a top view of the centrifugal fan impeller in the embodiment of the present disclosure. FIG. 5 is a perspective view schematically showing one representative blade on the back plate in the embodiment of the present disclosure. FIG. 6 is a schematic perspective view for explaining the shape of the blade in the embodiment of the present disclosure in more detail. FIG. 7 is a perspective view showing a curved surface having a positive Gaussian curvature. FIG. 8 is a perspective view showing a curved surface having a negative Gaussian curvature. FIG. 9 is a perspective view showing the surface of the blade in which the concave area and the convex area are connected along the direction of the rotation axis. FIG. 10 is a perspective view showing a blade having a surface whose curvature in the direction of the rotation axis is zero. FIG. 11 is a perspective view showing a blade having two convex areas sandwiching one concave area. FIG. 12 is a perspective view showing another example of the “S-shaped blade”. FIG. 13 is a diagram schematically illustrating a configuration example of an embodiment of a centrifugal fan according to the present disclosure. FIG. 14 is a graph showing “inlet / outlet pressure difference” in each of the comparative example and the example. FIG. 15 is a graph showing “axis output” in each of the comparative example and the example. FIG. 16 is a graph showing “efficiency” in each of the comparative example and the example. FIG. 17 is a graph showing the “sound pressure level” in each of the comparative example and the example.

  Hereinafter, an embodiment of a centrifugal fan impeller according to the present disclosure will be described. In the following description, a more detailed description than necessary may be omitted. For example, detailed descriptions of already well-known matters and repeated descriptions for substantially the same configuration may be omitted. This is to avoid the following description from becoming unnecessarily redundant and to facilitate understanding by those skilled in the art. The inventors provide the accompanying drawings and the following description to enable those skilled in the art to fully understand the present disclosure. They are not intended to limit the claimed subject matter.

<Centrifuge fan impeller>
First, FIG. 1 and FIG. 2 will be referred to. FIG. 1 is a perspective view of a centrifugal fan impeller 100 in the present embodiment. FIG. 2 is a perspective view showing a part (half) of the centrifugal fan impeller 100. A “centrifugal fan impeller” is sometimes referred to as a multiblade fan or a sirocco fan. As shown in FIG. 1, the centrifugal fan impeller 100 in the present embodiment has a rotation shaft (center shaft) 10 and rotates around the rotation shaft 10 by an electric motor (not shown) or the like during operation. . The rotating shaft 10 is not a rotating shaft but a virtual straight line located at the center of rotation. FIG. 2 schematically shows a configuration in which the centrifugal fan impeller 100 is cut by a plane including the rotating shaft 10.

  1 and 2 show XYZ coordinates composed of an X axis, a Y axis, and a Z axis that are orthogonal to each other for reference. In the illustrated example, the rotation axis 10 is parallel to the Z axis, and the plane orthogonal to the rotation axis 10 is parallel to the XY plane. The direction of the rotating shaft 10 shown in the figure does not limit the posture of the centrifugal fan impeller 100 during actual use. In the present disclosure, “the direction of the rotation axis” means “a direction parallel to the rotation axis”. The “radial direction” means “a direction of a half line extending from the rotation axis in a direction perpendicular to the rotation axis”. The “radial direction” is parallel to the XY plane shown.

  The centrifugal fan impeller 100 in the present embodiment includes a ring 12, a back plate 14, and a plurality of fan blades 20. Hereinafter, for simplicity, the fan blade is referred to as a “blade”.

  The ring 12 has a ring shape defined by an inner diameter, an outer diameter, and a thickness. The inner diameter defines a circular opening. The ring 12 can typically be formed from a synthetic resin material and / or a metal material.

  The back plate 14 has a generally disk shape defined by the outer diameter and thickness. The back plate 14 does not need to be a flat plate, and may have a central portion raised in a convex shape as shown in FIG. Further, ribs or grooves may be formed in a part of the back plate 14. The back plate 14 can also typically be formed from a synthetic resin material and / or a metal material.

  The plurality of blades 20 are arranged around the rotation axis 10 between the ring 12 and the back plate 14. In a typical example, the arrangement of the blades 20 is axisymmetric with respect to the rotation axis 10. In the present embodiment, the individual blades 20 have the same shape and size, and the posture of the individual blades 20 with respect to the rotating shaft 10 is common among all the blades 20. The distance from the rotating shaft 10 to each braid 20 is also the same. However, the individual blades 20 do not have to have the same shape as long as the rotational axis 10 is axisymmetric. In the example shown in FIG. 1, the number of blades 20 is 19, but the number of blades 20 is not limited to this example. The blade 20 may typically be formed from a synthetic resin material, a metal material, wood, or a composite material. Examples of composite materials include reinforced resins such as fiber reinforced plastics (eg FRP, CFRP).

  Reference is now made to FIGS. FIG. 3 is a schematic diagram illustrating a cross-sectional configuration example of the centrifugal fan impeller 100. FIG. 4 is a schematic view showing the upper surface of the centrifugal fan impeller 100.

  As shown in FIG. 3, each blade 20 includes a front edge 21 located radially inward, a rear edge 22 located radially outside, a first end 23 connected to the ring 12, and a back plate. 14 and a second end 24 connected to 14. “The radially inner side” and “the radially outer side” are “a side closer to the rotating shaft 10” and “a side farther from the rotating shaft 10”, respectively. Each blade 20 has a front surface 25 and a back surface 26 defined by a front edge 21, a rear edge 22, a first end 23, and a second end 24. In the present disclosure, the surface 25 of each blade 20 is a surface located on the pressure side when the centrifugal fan impeller 100 is rotating. The back surface 26 of each blade 20 is a surface located on the decompression side when the centrifugal fan impeller 100 is rotating. The front surface 25 and the back surface 26 may be referred to as a first surface 25 and a second surface 26, respectively.

  In FIG. 3, the blade 20 located on the left side of the rotation shaft 10 has a surface 25 that moves from the back of the drawing to the front by rotation and functions as a pressure surface on the front side of the drawing. On the other hand, the blade 20 located on the right side of the rotating shaft 10 has a back surface 26 that moves from the front to the back in the drawing by rotation and functions as a decompression surface on the front side.

  In FIG. 3, the direction of the airflow is schematically shown by four white arrows. The opening of the ring 12 functions as an airflow inlet (inlet). Air or other gas taken into the inside from the inlet flows radially outward by the rotation of the impeller 100 and is blown out from the impeller 100.

  As shown in FIG. 4, the blade 20 of the present embodiment is a swept wing. In the swept wing, the trailing edge 22 is located rearward of the leading edge 21 in the direction of rotation. On the contrary, the advancing blade has the trailing edge 22 positioned in front of the leading edge 21 in the direction of rotation. In the straight wing, the leading edge 21 and the trailing edge 22 are located on the same radial straight line.

  The length from the leading edge 21 to the trailing edge 22 of each blade 20 is called a “chord length”. The size of the blade 20 in the direction of the rotating shaft 10 and the chord length can be appropriately determined according to the size of the space in which the centrifugal fan impeller is disposed.

  Reference is now made to FIGS. FIG. 5 is a perspective view schematically showing only one representative blade 20 to which the back plate 14 is coupled in the present embodiment. FIG. 6 is a schematic perspective view for explaining the shape of the blade 20 in more detail.

  As shown in FIG. 6, the surface 25 of the blade 20 includes a convex surface region 30 having a positive curvature in the direction of the rotation shaft 10 and a concave surface region 32 having a negative curvature in the direction of the rotation shaft 10. Yes. The convex surface region 30 and the concave surface region 32 are smoothly connected along the direction of the rotating shaft 10. In the present disclosure, “curvature is positive” in the direction of the rotation axis means that the position of the center of curvature of the curve along the direction of the rotation axis is observed on this surface when the observer faces the surface to be observed. It means that it is located behind the surface as viewed from the person. In addition, “the curvature is negative” in the direction of the rotation axis means that when the observer directly faces the surface to be observed, the position of the center of curvature of the curve along the direction of the rotation axis on the surface is from the observer. It means that it is located in front of that surface.

  Similarly to the front surface 25, the back surface 26 of the blade 20 has a convex surface region 30 having a positive curvature in the direction of the rotating shaft 10 and a concave surface region 32 having a negative curvature in the direction of the rotating shaft 10. However, the convex surface area 30 of the back surface 26 is located behind the concave surface area 32 of the front surface 25. Further, the concave area 32 of the back surface 26 is located on the back side of the convex area 30 of the front surface 25. In the present embodiment, the convex surface region 30 on the front surface 25 and the concave surface region 32 on the back surface 26 constitute the upper half of the blade 20, and the concave surface region 32 on the front surface 25 and the convex surface region 30 on the back surface 26 are approximately. The lower half of the blade 20 is configured in a parallel relationship.

  As described above, the blade 20 in the present embodiment is not a straight blade extending in a planar shape in the radial direction but a retracted blade. For this reason, each of the front surface 25 and the rear surface 26 of the blade 20 has a value in which the curvature in the radial direction is not zero. Note that the fan blade in the present disclosure is not limited to the backward blade, and may be a forward blade. Alternatively, a straight wing as shown in FIG. According to the inventors' experiments, the most excellent aerodynamic characteristics and noise characteristics are exhibited when the blade is a swept wing.

  FIG. 7 is a perspective view showing a curved surface 300 having a positive Gaussian curvature, and FIG. 8 is a perspective view showing a curved surface 320 having a negative Gaussian curvature. The Gaussian curvature is represented by the product of the maximum curvature value and the minimum curvature value at each point. The Gaussian curvature at each point on the convex area may be roughly positive, and a point or area where the Gaussian curvature is not positive may be included in part. Similarly, the Gaussian curvature at each point on the concave area may be roughly negative, and a point or area where the Gaussian curvature is not negative may be included in part. In a typical example, the ratio of the area having a positive Gaussian curvature to the convex area and the ratio of the area having a negative Gaussian curvature to the concave area are both 80% or more.

  By connecting the convex surface area defined by the curved surface 300 and the concave surface area defined by the curved surface 320 in the direction of the rotating shaft 10, a blade that curves in an S shape along the direction of the rotating shaft 10 is realized. Various modifications can be realized by changing the order of connection.

  FIG. 9 shows another example of the surface 25 of the blade 20 in which the concave region 32 and the convex region 30 are connected along the direction of the rotation axis 10. The vertical arrangement of the concave surface area 32 and the convex surface area 30 in the blade 20 of FIG. 9 is a relationship in which the vertical arrangement of the concave surface area 32 and the convex surface area 30 in the blade 20 of FIG.

  For reference, FIG. 10 shows a blade 20C having a surface 25 with zero curvature in the direction of the axis of rotation 10. Here, it is assumed that the height of the blade 20C in the direction of the rotary shaft 10 is equal to the height of the blade 20 in FIG. At this time, since the curvature of the blade 20 in the direction of the rotating shaft 10 is not 0, the surface area of the blade 20 is larger than the surface area of the blade 20C.

  The Gaussian curvature shown by the front surface 25 and the rear surface 26 of the blade 20 (see, for example, FIG. 9) in the embodiment of the present disclosure is 1. It is determined to have a surface area of 01 times or more, preferably 1.1 times or more.

  FIG. 11 shows the blade 20 having two convex areas 30 sandwiching one concave area 32. These convex surface areas 30 and concave surface areas 32 are alternately arranged along the direction of the rotation axis 10. The blade 20 also has a portion that curves in an S shape along the direction of the rotary shaft 10. In the present disclosure, the portion curved in an S shape extends from the front edge 21 of the blade 20 to the rear edge 22. In the present application, a blade in which a portion curved in an S shape along the direction of the rotary shaft 10 extends from the front edge 21 to the rear edge 22 is referred to as an “S-shaped blade”. In the example of FIG. 11, one of the number of convex surface regions 30 and the number of concave surface regions 32 included in each of the front surface 25 and the back surface 26 of the blade 20 is plural. Embodiments of the present disclosure are not limited to this example. There may be a plurality of at least one of the number of the convex surface regions 30 and the number of the concave surface regions 32 of each of the front surface 25 and the back surface 26 of the blade 20.

  FIG. 12 shows another example of the “S-shaped blade”. A blade 20F in FIG. 12 is a straight wing type S-shaped blade. The curvature of the surface of the blade 20F is 0 in the direction parallel to the plane orthogonal to the rotation axis 10. For this reason, the Gaussian curvature of the blade 20F is zero. However, the blade 20 </ b> F also has a portion that curves in an S shape along the direction of the rotating shaft 10 from the front edge 21 to the rear edge 22. Accordingly, the blade 20F in which the Gaussian curvature of the convex surface region 30 and the Gaussian curvature of the concave surface region 32 are both zero is also included in the broad “S-shaped blade”.

  In the example of FIG. 12, the cut surface obtained by cutting the blade 20F along a plane orthogonal to the rotation shaft 10 extends linearly in the same direction regardless of the position of the cut surface. However, the direction in which the cut surface in the vicinity of the first end portion 23 extends does not have to coincide with the direction in which the cut surface in the vicinity of the second end portion 24 extends, and these may be twisted. Such a twist may be included in the blade 20 shown in FIGS. 6, 9, and 11.

<Centrifuge fan>
FIG. 13 is a diagram schematically illustrating a configuration example of an embodiment of a centrifugal fan according to the present disclosure.

  The centrifugal fan 1000 in this embodiment includes the impeller 100 described above, a casing 200 that houses the impeller 100, and a motor 300 that rotates the impeller 100. The configuration of the motor 300 is not particularly limited, and can have various structures.

  An arrow of a one-dot chain line in FIG. 13 indicates a rotation direction of the impeller 100. Air or other gas exiting from the impeller 100 is discharged from the outlet 220 of the casing 200. The outlet of the casing 200 can be connected to a duct (not shown) or the like.

14 to 17 are graphs showing numerical fluid dynamics simulation results obtained for the example of the centrifugal fan and the comparative example of the present embodiment. The embodiment is a centrifugal fan including the centrifugal fan impeller shown in FIG. On the other hand, the comparative example is a centrifugal fan including a centrifugal fan impeller including a blade (see FIG. 10) whose curvature in the direction of the rotation axis is zero. More specific parameters are as follows.
Ring outer diameter, inner diameter, thickness = 280mm, 125mm, 2mm
Blade length, chord length, thickness = 100mm, 72mm, 2mm
Number of blades = 19 Rotation speed = 1380 rpm
Working fluid = Air

Incidentally, the surface area per one fan (one side) is, 13748Mm ² in Example, a 13530Mm ² in Comparative Example.

  FIG. 14 is a graph showing “inlet / outlet pressure difference” in each of the comparative example and the example. The pressure difference at the inlet / outlet is a value obtained by subtracting the pressure at the center of the opening of the ring 12 from the pressure at the outlet 220 in FIG. The unit of pressure difference is Pascal (Pa). As is apparent from FIG. 14, according to the embodiment, the pressure difference at the inlet / outlet increases.

FIG. 15 is a graph showing “axis output” in each of the comparative example and the example. The shaft output is the motor output (power consumption) when the volume flow rate of the gas is 0.167 [m ³ / s]. The unit is watt (W). As is apparent from FIG. 15, according to the embodiment, it is possible to reduce the power consumption required to realize the same volume flow rate.

  FIG. 16 is a graph showing “efficiency” in each of the comparative example and the example. Efficiency is the “ratio of converting shaft output to fluid energy”. The unit is percent (%). As is apparent from FIG. 16, the efficiency increases according to the embodiment.

FIG. 17 is a graph showing the “sound pressure level” in each of the comparative example and the example. The sound pressure level is represented by 20 × log ₁₀ (P / P0) where the reference pressure P0 is 20 × 10 ⁻⁶ and the noise peak pressure is P. The unit is decibel (dB). As is apparent from FIG. 17, according to the embodiment, noise is reduced under the same operating conditions.

  As described above, according to the embodiment of the centrifugal fan of the present disclosure, under the same operating condition, the pressure difference at the inlet / outlet is increased as compared with the centrifugal fan having a non-S-curved blade, the shaft output is reduced, It is possible to achieve at least one of increasing efficiency and reducing noise.

  The centrifugal fan impeller of the present disclosure can be suitably used for various centrifugal fans. Moreover, according to this indication, the centrifugal fan excellent in the aerodynamic characteristic and / or the noise characteristic can be provided.

10 axis of rotation
12 Ring 14 Back plate 20 Fan blade 21 Blade leading edge 22 Blade trailing edge 23 Blade first end 24 Blade second end 25 Blade surface 26 Blade back surface 100 Centrifugal fan impeller 200 Casing 300 Motor 1000 Centrifugal fan

Claims (6)

A centrifugal fan impeller having a rotating shaft,
Ring,
A back plate,
A plurality of fan blades arranged around the rotation axis between the ring and the back plate;
With
Each of the plurality of fan blades is
A radially inner leading edge;
A radially outer trailing edge;
A first end connected to the ring;
A second end connected to the back plate;
Front and back surfaces each defined by the leading edge, the trailing edge, the first end, and the second end;
Have
Each of the front surface and the back surface has a convex surface region having a positive curvature in the direction of the rotation axis and a concave surface region having a negative curvature in the direction of the rotation axis, and the convex surface region and the concave surface region. Are centrifugal fan impellers connected along the direction of the rotation axis.   The centrifugal fan impeller according to claim 1, wherein the plurality of fan blades are forward blades or backward blades.   The centrifugal fan impeller according to claim 1 or 2, wherein a Gaussian curvature of the convex region is positive and a Gaussian curvature of the concave region is negative.   The centrifugal fan impeller according to claim 1, wherein the Gaussian curvature of the convex surface region and the Gaussian curvature of the concave surface region are both zero.   At least one of the number of the convex surface regions and the number of the concave surface regions that each of the front surface and the back surface has is plural, and the convex surface regions and the concave surface regions are alternately arranged along the direction of the rotation axis. The centrifugal fan impeller according to any one of claims 1 to 4. A motor,
A centrifugal fan impeller coupled to the motor;
A casing for accommodating the centrifugal fan impeller;
With
The centrifugal fan impeller is a centrifugal fan impeller according to any one of claims 1 to 5.

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