JP2019019758A - Centrifugal fan impeller and centrifugal fan with centrifugal fan impeller - Google Patents

Abstract

To improve shaft output and efficiency at an operation point of a centrifugal fan.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 is a sweptback blade. A distance R from the rotation axis 10 to a rear edge 22 of the blade 20 is expressed by R(h) as a function of a height h from the back plate 14. When the height of the blade 20 from the back plate 14 is defined as H, the size of R(h) at the position of a first end 23 of the blade 20 is defined as R(H) and the size of R(h) at the position of a second end 24 of the blade 20 is defined as R(0), |R(H)-R(0)|/H is equal to or more than 0.1.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 2002-349486 A

  Embodiments of the present disclosure provide a centrifugal fan impeller with improved shaft output and efficiency at an operating point, 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. The plurality of fan blades are swept blades, and a distance R from the rotation axis to the trailing edge of the fan blade is expressed by R (h) that is a function of a height h from the back plate. The height of the fan blade from the back plate is H, the size of R (h) at the position of the first end of the fan blade is R (H), and the position of the second end of the fan blade Where R (h) is R (0), | R (H) −R (0) | / H is 0.1 or more.

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

  According to the embodiment of the present disclosure, the shaft output and the efficiency at the operating point of the centrifugal fan impeller can be improved.

FIG. 1 is a perspective view of a centrifugal fan impeller in an embodiment of the present disclosure. FIG. 2 is a side view 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 diagram for explaining the shape of the blade in the embodiment of the present disclosure in more detail. FIG. 7 is a diagram schematically illustrating a configuration example of an embodiment of a centrifugal fan according to the present disclosure. FIG. 8 is a graph showing “inlet / outlet pressure difference” in each of the comparative example and the example. FIG. 9 is a graph showing “axis output” in each of the comparative example and the example. FIG. 10 is a graph showing “efficiency” in each of the comparative example and the example. FIG. 11 is a perspective view showing a representative blade in a comparative example. FIG. 12 is a perspective view showing the S-shaped blade in which the concave area and the convex area are connected along the direction of the rotation axis.

  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 side view 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.

  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 that is raised in a convex shape. 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 blade 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 36, 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 coupled to the back plate 14 in the present embodiment. FIG. 6 is a schematic diagram for explaining the shape of the blade 20 in more detail.

  As shown in FIGS. 5 and 6, the position of the first end 23 of the blade 20 in this embodiment is shifted radially outward from the position of the second end 24. In other words, the distance from the rotating shaft 10 to the center of the first end 23 of the blade 20 is longer than the distance from the rotating shaft 10 to the center of the second end 24 of the blade 20.

  In the illustrated example, the leading edge 21 and the trailing edge 22 of the blade 20 are not parallel to the direction of the rotating shaft 10 but are inclined with respect to the rotating shaft 10. As shown in FIG. 6, when the angle between the leading edge 21 of the blade 20 and the direction of the rotating shaft 10 is θL, and the angle between the trailing edge 22 of the blade 20 and the direction of the rotating shaft 10 is θT, In this embodiment, θL is, for example, not less than 1 ° and not more than 45 °, and θT is, for example, not less than 1 ° and not more than 45 °. θL and θT may be the same or different.

  When the distance from the rotary shaft 10 to the rear edge 22 of the blade 20 is R, the distance R changes according to the height h from the back plate 14. This distance R can be expressed by R (h) which is a function of the height h. In the present embodiment, R (h) shows the largest value at the position (h = H) of the first end 23 of the blade 20, and is smallest at the position (h = 0) of the second end 24 of the blade 20. The value is shown. A typical example of R (h) in this case is a monotonically increasing function. However, when unevenness is formed on the trailing edge 22, R (h) is a complex function. R (h) in the present embodiment can be approximately expressed as a × h + b [mm] when the unit of length is millimeter (mm). The most important point in the present disclosure is that the position of the first end portion 23 is shifted in the radial direction from the position of the second end portion 24 while the blade 20 has a curved surface constituting a swept wing. is there. For this reason, the function form of R (h) is not limited to the above example.

  The centrifugal fan impeller 100 of the present disclosure is not limited to the above example. R (h) may be a function that decreases as h increases. In the present disclosure, the centrifugal fan impeller 100 in which R (h) is an increasing function has a “positive gradient”, and the centrifugal fan impeller 100 in which R (h) is a decreasing function has a “reverse gradient”. Define.

  When the chord length at the first end 23 of the blade 20 is C1, the chord length at the second end 24 of the blade 20 is C2, and the length (height) of the blade 20 in the direction of the rotary shaft 10 is H. , C1 / H and C2 / H are each not less than 0.1 and not more than 0.9, for example. In the embodiment of the present disclosure, when the ratio of the chord length to the height H of the blade 20 is relatively small, an effect of preventing performance degradation due to separation of the flow around the blade is obtained. Note that C1 and C2 may be equal or different. The thickness of the blade 20 is, for example, not less than 0.1 mm and not more than 10 mm.

  The blade 20 in this embodiment is not a straight blade extending in a planar shape in the radial direction, but a retracted blade. According to the simulation results of the inventor, the shaft output and the efficiency can be improved when the swept wing is used and when | R (H) −R (0) | / H has a gradient of 0.1 or more. I understood. | R (H) −R (0) | / H can be set, for example, in the range of 0.1 to 2.0. In particular, when | R (H) −R (0) | / H is in the range of 0.2 to 1.0, excellent characteristics can be realized. Such an effect is realized when the direction of the chord defined by the leading edge 21 and the trailing edge 22 of the blade 20 is retreated by an angle of 5 degrees to 70 degrees with respect to the radial direction. I understand.

<Centrifuge fan>
FIG. 7 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.

  The arrow of the alternate long and short dash line in FIG. 7 indicates the 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.

  8 to 10 are graphs showing numerical fluid dynamics simulation results obtained for the example of the centrifugal fan and the comparative example of the present embodiment. Model No. 1, no. 2, no. 3, no. For 4, the simulation was performed. The characteristic points of each model are as follows.

  Model No. Reference numeral 1 denotes a centrifugal fan including the centrifugal fan impeller shown in FIGS. 1 and 2. Model No. 2 is model no. The centrifugal fan impeller of 1 is modified to a reverse gradient. In contrast, model no. Reference numeral 4 denotes a centrifugal fan impeller provided with a blade 20C parallel to the rotating shaft 10 as shown in FIG. Model No. 3 has a positive slope as shown in FIG. 2, but the model No. 3 is that the blade is a forward wing. Different from 1. Model No. 1 and no. 2 corresponds to the example, and the model No. 3 and no. 4 corresponds to a comparative example.

The following parameters are common to all models.
Ring outer diameter, inner diameter, thickness = 280mm, 125mm, 2mm
Blade length, chord length, thickness = 100mm, 46mm, 2mm
Number of blades = 36 Rotation speed = 1500 rpm
Working fluid = Air

FIG. 8 is a graph showing the “pressure difference at the inlet / outlet” in each model. 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. 8, in the embodiment, the pressure difference at the inlet / outlet at the operating point is reduced. Note that. The “operating point” is an intersection of “system impedance” and “air volume-static pressure characteristic curve” in the model used for the simulation. The “operating point” in the graph corresponds to the operating state when the volume flow rate of the working fluid (air) is 600 [m ³ / h].

  FIG. 9 is a graph showing “axis output” in each model. The unit is watt (W). As is apparent from FIG. 9, according to the embodiment, it is possible to reduce the power consumption required to realize the same volume flow rate.

  FIG. 10 is a graph showing “efficiency” in each model. Efficiency is the “ratio of converting shaft output to fluid energy”. The unit is percent (%). As is apparent from FIG. 10, the efficiency increases according to the embodiment.

  As described above, according to the embodiment of the centrifugal fan of the present disclosure, the pressure difference at the inlet / outlet is reduced under the same operating condition as compared with the centrifugal fan in which the blade is parallel to the rotation axis, but the shaft output is reduced. Efficiency.

  In the embodiment of the present disclosure, for example, a blade 20 curved in an S shape along the direction of the rotation shaft 10 as illustrated in FIG. 12 may be used. The blade 20 has a shape in which a convex surface region 30 having a positive Gaussian curvature and a concave surface region 32 having a negative Gaussian curvature are connected in the direction of the rotary shaft 10. By arranging such blades 20 so as to be inclined with respect to the rotary shaft 10, the surface area of the blades 20 is effectively increased, so that higher efficiency can be realized.

  In order to reduce aerodynamic noise, a plurality of serration rows may be formed on at least one of the leading edge 21 and the trailing edge 22.

  The centrifugal fan impeller of the present disclosure can be suitably used for various centrifugal fans. Moreover, according to this indication, the centrifugal fan which improved the axial output and efficiency in an operating point 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 (4)

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
The plurality of fan blades are swept wings;
The distance R from the rotational axis to the trailing edge of the fan blade is represented by R (h), which is a function of the height h from the back plate,
The height of the fan blade from the back plate is H,
The size of R (h) at the position of the first end of the fan blade is R (H),
When the size of R (h) at the position of the second end of the fan blade is R (0),
| R (H) −R (0) | / H is a centrifugal fan impeller having a value of 0.1 or more. The chord length at the first end of the fan blade is C1,
The chord length at the second end of the fan blade is C2,
When the length of the fan blade in the direction of the rotation axis is H,
The centrifugal fan impeller according to claim 1, wherein C1 / H and C2 / H are 0.1 or more and 0.9 or less, respectively.   The centrifugal fan impeller according to claim 1 or 2, wherein a chord direction defined by a leading edge and a trailing edge of the fan blade is retreated by an angle of 5 degrees or more and 70 degrees or less with respect to a radial direction. . 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 3.

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