JP2018168764A - Blower - Google Patents

Abstract

In a conventional blower, sound generated on a positive pressure surface on the outer peripheral side of a leading edge is reflected by a side wall of a bell mouth and radiated to the front of the blower. A blower 1 includes a propeller fan 5 body and a bell mouth 6 surrounding the outer periphery of the propeller fan 5. The shape of a cross section of the bell mouth 6 cut along a plane including a rotating shaft 2 is from the suction side. A curved first R portion 8 having a concave inner surface of the bell mouth 6, a first linear portion 9 having a linear shape connected thereto, and a curved shape having a convex surface on the inner side of the bell mouth 6 connected to the first straight portion 9. The second R portion 10 and the second straight portion 11 tangent to the second R portion 10 are parallel to the rotation axis 2 and have a linear shape. The angle A + the angle B <90 ° is set. By doing so, the first reflected sound 19 can diffuse the sound toward the outside of the front, and the sound at the front can be reduced. [Selection] Figure 1

Description

  The present invention relates to a blower including a bell mouth and a propeller fan.

  Conventionally, this type of blower has a configuration described in Patent Document 1, for example, as the shape of a bell mouth for the purpose of noise reduction.

  The configuration will be described below with reference to FIG.

  FIG. 6 shows a cross-sectional view including a rotary shaft 101 of a conventional blower and cut along a plane including the rotary shaft 101.

  As shown in FIG. 6, there is a bell mouth 103 surrounding the outer periphery of the propeller fan 102, and the cross-sectional shape of the bell mouth 103 has a center of curvature radius from the suction side to the inside of the bell mouth 103, and the inside of the bell mouth 103 is The first R portion 104 curved in a concave shape and the center of the radius of curvature outside the bell mouth 103 connected to the first R portion 104, the second R portion 105 curved inside the bell mouth 103 and the rotation axis connected to it 101 includes a straight line portion 106 parallel to 101. In such a configuration, since the bell mouth 103 has the first R portion 104, the space around the propeller fan 102 on the suction side can be widened. For this reason, the airflow flows not only from the front side of the propeller fan 102 but also from the side surface, and the suction area is increased to reduce the noise due to the reduction of the suction wind speed. Further, the first R portion 104 of the propeller fan 102 is further reduced. In the vicinity, since the space is wide, the pressure fluctuation is alleviated, turbulence of the airflow flowing into the propeller fan 102 can be suppressed, and noise can be reduced.

JP 2011-185236 A

  In the conventional device for reducing the noise of a blower provided with a bell mouth and a propeller fan, the fluctuation of the gas flowing from the outer peripheral edge of the wing provided to the propeller fan to the rotation region of the propeller fan is suppressed. Low noise performance because the flow flowing along the suction side wall and the sound generated at the front edge of the propeller fan positive pressure surface are reflected on the bell mouth side wall and propagated to the front of the blower. I couldn't get enough.

  Then, an object of this invention is to provide the air blower which can reduce the sound of an air blower front.

  In order to achieve this object, the present invention provides a propeller fan body having a plurality of blades whose front edges are advanced in the rotation direction, and a bell mouth surrounding an outer periphery of the propeller fan. The bell mouth has a first R portion, a first straight portion, a second R portion, a second R portion, and a second R portion, in a cross-sectional shape cut by a plane including the rotation axis, from the suction side to the outlet side end portion. The first R portion has a curved shape in which the maximum distance from the rotation axis is Ra and the inside of the bell mouth is a concave surface, and the first straight portion is the first straight portion. The side with the small angle formed with the plane perpendicular to the rotation axis connected to the R portion is the angle A, and has a linear shape inclined from the outside to the inside of the bell mouth toward the blowing side, and the second R portion is A curve that leads to the first straight part and the inside of the bell mouth is a convex surface The second straight portion is tangent to the second R portion and has a straight shape parallel to the rotation axis, and the outer diameter Df of the propeller fan and the maximum distance Ra are Ra / Df ≦ 0.85, and the distance from the rotary shaft to the outer peripheral edge of the front edge of the propeller fan is shorter than the distance from the rotary shaft to the contact point between the second R portion and the first linear portion, The outer angle of the corner formed by the straight line formed by connecting the outer peripheral end of the front edge and the contact point of the second R portion and the first straight portion and the first straight portion is the corner B, and the corner A and the corner B are A + angle B <90 °, which achieves the intended purpose.

  ADVANTAGE OF THE INVENTION According to this invention, the air blower which can reduce the sound of an air blower front can be provided.

The perspective view seen from the suction side of the air blower of Embodiment 1 of this invention Sectional drawing of the principal part of the air blower of Embodiment 1 of this invention. Enlarged view of the bell mouth part of Fig. 2 The figure explaining the reflection of the sound of the bellmouth part of FIG. Sectional drawing which showed the reflection effect of the sound in Embodiment 1 of this invention Sectional drawing which shows the structure of the conventional air blower

  A blower device according to claim 1 of the present invention includes a propeller fan main body having a plurality of blades whose front edges are advanced in the rotation direction, and a bell mouth surrounding an outer periphery of the propeller fan. The bell mouth has a first R portion, a first straight portion, a second R portion, and a second straight line from a suction side to a blow-off end portion in a cross-sectional shape cut by a plane including the rotation axis. The first R portion has a curved shape in which the maximum distance from the rotation axis is Ra and the inside of the bell mouth is a concave surface, and the first straight portion is the first R portion. The side having a small angle with the plane perpendicular to the rotation axis is an angle A, and is a linear shape inclined from the outer side to the inner side of the bell mouth. It has a curved shape that is connected to a straight line and the inside of the bellmouth is convex. The second straight portion is tangent to the second R portion and has a linear shape parallel to the rotational axis, and the outer diameter Df of the propeller fan and the maximum distance Ra are Ra / Df ≦ 0. 85, and the distance between the rotating shaft and the outer peripheral edge of the front edge of the propeller fan is shorter than the distance from the rotating shaft to the contact point between the second R portion and the first linear portion, and the outer edge of the front edge of the propeller fan. And the outer angle of the angle formed between the straight line formed by connecting the second R portion and the contact of the first straight portion and the first straight portion is the angle B, and the angle A and the angle B are the angle A + the angle B <90 °.

  Thereby, the disturbance of the flow flowing along the suction side wall portion of the bell mouth is suppressed by the first straight portion, and the first straight portion reflects the sound radiated from the leading edge positive pressure surface at an angle that diffuses to the surroundings. The sound propagating to the front of the blower can be diffused around.

  In the air blower according to claim 2, the curvature radius R1 of the second R portion is a ratio of the radial distance Rst2 in the axial direction of the second linear portion, and R1 / Rst2 ≧ 0.12. It is characterized by.

  As a result, the air flow on the suction side of the bell mouth can be smoothly collected on the pressure surface of the wing to suppress the disturbance of the flow, and the sound of the blower can be reduced.

  The blower according to claim 3 is characterized in that the center of the radius of curvature of the first R portion is at the outer peripheral edge of the front edge of the blade.

  Thereby, the first R portion reflects the sound radiated from the pressure surface of the leading edge to the pressure surface of the wing of the propeller fan, and the reflected sound is emitted to the blowing side, thereby reducing the sound in front of the blower. it can.

  Further, in the blower according to claim 4, a line connecting the contact point between the outer peripheral end of the blade and the second straight part of the second R part is a contact point with the second straight part of the second R part. It is characterized by being a normal line.

  As a result, the second R portion reflects the sound radiated from the pressure surface of the leading edge to the pressure surface of the wing of the propeller fan, and the reflected sound is emitted to the blowing side to reduce the sound in front of the blower. be able to.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(Embodiment 1)
FIG. 1 is a perspective view seen from the suction side of the blower according to Embodiment 1 of the present invention. FIG. 2 is a cross-sectional view of main parts of the blower according to Embodiment 1 of the present invention. FIG. 3 is an enlarged view of the bell mouth portion of FIG.

  FIG. 4 is a diagram for explaining the reflection of sound from the bell mouth portion of FIG. FIG. 5 is a cross-sectional view showing the sound reflecting action in the first embodiment of the present invention (cross-sectional view showing the sound reflection in FIG. 3).

  As shown in FIG. 1, the blower 1 includes a propeller fan 5 main body including a plurality of blades 4 that rotate about a rotating shaft 2 and that have a leading edge 3 advanced in the rotation direction, and a bell that surrounds the outer periphery of the propeller fan 5. And a mouse 6.

  The air flow 7 flows in from the front and front edges 3 in FIG. 1 and flows out backward.

  As shown in FIG. 2, in the cross section cut along the plane including the rotation axis 2, the shape of the bell mouth 6 is connected to the curved first R portion 8 in which the inside of the bell mouth 6 is concave from the suction side. A linear first linear portion 9, a curved second R portion 10 connected to the first linear portion 9 and having a convex inner surface of the bell mouth 6, and a tangent to the second R portion 10, and the rotation axis 2 It is the 2nd straight part 11 which is parallel and linear shape.

  As shown in FIG. 3, the first straight portion 9 has a small angle formed with the surface 12 perpendicular to the rotation axis as the angle A <b> 13, and is a straight line inclined toward the blowout side from the outer peripheral side to the inner peripheral side of the bell mouth 6. Shape.

  Further, the outer diameter Df of the propeller fan 5 and the maximum distance Ra from the rotation shaft 2 of the first R portion 8 are in a relationship of Ra / Df ≦ 0.85.

  In the cross section cut along the plane including the rotation shaft 2 of the propeller fan 5, the position of the front edge 3 of the blade 4 that is closest to the suction side in the axial direction is the front edge outer peripheral end 14. The distance from the rotating shaft 2 to the outer peripheral end 14 of the front edge of the propeller fan 5 is shorter than the distance from the rotating shaft 2 to the contact 15 of the first linear portion and the second R portion. Furthermore, the outer angle of the angle formed by the first straight portion 9 and the straight line formed by connecting the outer peripheral end 14 of the front edge of the propeller fan 5 and the contact 15 of the first straight portion and the second R portion is the angle B16, The angle B16 has a configuration of angle A13 + angle B16 <90 °.

  Since the bell mouth 6 and the propeller fan 5 have a larger space on the suction side than the blow side, air along the bell mouth 6 flows inside the bell mouth 6, that is, there is a side airflow 17. As the propeller fan 5 rotates, the turbulence is suppressed by the side airflow 17 flowing along the first R portion 8 and the first straight portion 9 of the bell mouth 6. The air smoothly flows into the pressure surface of the blade 4, is pressurized by the blade 4, and flows out to the blowing side. The second straight portion 11 becomes a wall so that the airflow boosted by the blade 4 does not diffuse in the radial direction, and the airflow on the outer peripheral side of the blade 4 flows along the second straight portion 11, so that a large amount of airflow flows downstream. Can carry.

  Next, generation and propagation of sound generated at the outer peripheral edge 14 of the leading edge will be described with reference to FIGS. 1, 3, 4, and 5.

  In FIG. 1, air flows from the leading edge 3. If it demonstrates in detail, since the front edge 3 of the wing | blade 4 is moving forward in the rotation direction, air will flow in from the front edge outer periphery end 14 which is the front-end | tip of a rotation direction. Further, since the peripheral speed of the outer peripheral edge 14 of the front edge is high, the pressure fluctuation on the pressure surface of the outer peripheral edge 14 of the front edge into which air flows increases, and this is a source of noise.

  Since the pressure surface of the outer peripheral edge 14 of the front edge faces the blowout side, as shown in FIG. 4, the sound generated by the wings 4 is emitted to the blowout side and is emitted as it is from the bell mouth 6 to the blowout side. Then, there is a sound that spreads to the side of the bell mouth 6 and is reflected on the side wall of the bell mouth 6 due to the inclination of the surface of the side wall of the bell mouth 6. The sound reflected on the side wall of the bell mouth 6 is roughly divided into two directions, the first radiated sound 18 and the second radiated sound 20. One is the first reflected sound 19 reflected on the pressure surface of the blade 4, and the other is the second reflected sound 21 reflected on the front side, which is the suction side of the blower 1.

  The first radiated sound 18 generated on the pressure surface of the blade 4 is reflected as the first reflected sound 19 reflected on the side wall of the bell mouth 6 toward the pressure surface of the blade 4 and the pressure surface of the blade 4 facing the blowing direction. It is reflected by and discharged to the blowing side. The sound heard in the front is the first reflected sound 19 reflected from the side wall of the bell mouth 6 from the first radiated sound 18 generated on the pressure surface of the outer peripheral end 14 of the front edge. That is, the first reflected sound 19 from the first straight portion 9 closest to the front edge outer peripheral end 14 propagates to the front. The first reflected sound from the first linear portion 9 is set by setting an angle A13 formed by a first linear portion extension line 22 extending from the first linear portion 9 shown in FIG. It is possible to prevent 19 from propagating to the front.

  A method for setting the corner A13 will be described with reference to FIG.

  When the sound radiated from the outer peripheral end 14 of the leading edge is reflected as the first reflected sound 19 when the first radiated sound 18 incident on the contact 15 between the first straight portion and the second R portion is reflected as the first reflected sound 19, the reflected angle is reflected. Reflected at 23. In other words, the outer angle of the angle formed by the first straight portion 9 and the straight line formed by connecting the outer peripheral end 14 of the front edge of the propeller fan 5 and the contact 15 of the first straight portion and the second R portion is the angle B16. At this time, the angle B <b> 16 and the reflection angle 23 are the same with respect to the first straight line portion 9. The internal angles of the triangle formed by the reflected sound extension line 24 obtained by extending the first reflected sound 19 in the direction opposite to the sound traveling direction, the surface 12 perpendicular to the rotation axis, and the first straight line extension line 22 are an angle A13 and a reflection. This is the angle C25 formed by the diagonal of the corner 23 (equal to the corner B16), the reflected sound extension line 24, and the surface 12 perpendicular to the rotation axis. Focusing on the first reflected sound 19, by setting the angle C25 to be larger than 90 °, that is, by setting the angle A13 + angle B16 <90 °, the first reflected sound 19 diffuses the sound toward the outside of the front. It is possible to reduce the sound at the front.

  By setting the angle C25 at the contact point 15 of the first straight part and the second R part, the side farther from the rotation axis 2 of the first straight part 9 is reflected by the contact 15 of the first straight part and the second R part. Since the incident angle is smaller than the sound to be emitted, it is possible to reduce the sound in the front direction toward the outside in the radial direction. If the end point obtained by extending the first straight portion 9 in the outer peripheral direction is the end of the bell mouth 6, the same effect can be obtained up to the end of the bell mouth 6, but the product size becomes large.

  Therefore, by providing the first R portion 8 in the outer peripheral direction of the first straight portion 9, the product size can be reduced. That is, when the maximum distance from the rotating shaft 2 of the first R portion 8 is Ra, the relationship with the outer diameter Df of the propeller fan 5 is Ra / Df ≦ 0.85. The dimensions can be reduced. On the other hand, since it becomes the 1st R part 8 with a small curvature radius compared with what extended the 1st linear part 9 to the outer peripheral direction, if it flows into the outer peripheral side of the propeller fan 5 as it is, the turbulent flow will flow in. However, the presence of the first straight portion 9 allows the flow to flow along the bell mouth 6 and allow the flow with less turbulence to flow into the propeller fan 5.

  As an example, the diameter of the propeller fan 5 is 210 mm, the height of the propeller fan 5 in the axial direction is 80 mm, the maximum distance from the rotating shaft 2 of the bell mouth 6 is 175 mm, and from the outer peripheral end 14 of the leading edge, Assuming that the distance in the axial direction of the second R contact 15 is 60 mm and the distance in the radial direction is 23 mm, the angle B16 that is the incident angle of sound from the outer peripheral end 14 of the front edge to the first linear portion and the second R contact 15 is By setting the angle A13 to 10 ° at 79 °, the first reflected sound 19 is emitted to the outside of the front, so that the sound is diffused and the front sound can be reduced.

  In addition, when the radius of curvature R1 of the second R portion 10 is set, if the radius of curvature R1 is too small, the flow along the bell mouth 6 suddenly changes in the axial direction at the second R portion 10, so that the bell mouth 6, the flow is separated, the turbulent flow flows into the outer periphery of the propeller fan 5, and noise increases. Therefore, by making R1 / Rst2 ≧ 0.12 with respect to the radial distance Rst2 from the rotating shaft 2 of the second linear portion 11, it is possible to suppress the flow of turbulent flow into the propeller fan 5. .

  As an example, when Rst2 is 110 mm, the turbulent flow of R1 can be suppressed from flowing into the outer peripheral side of the propeller fan 5 by setting the curvature of R1 to a radius of 13 mm or more.

  Further, as shown in FIG. 3, the center of the radius of curvature r of the first R portion 8 is at the outer peripheral edge 14, so that the first R portion 8 is radiated from the pressure surface of the front outer periphery 14. Is reflected on the pressure surface of the blade 4 of the propeller fan 5, and the reflected sound is emitted to the blowout side, so that the sound in front of the blower can be reduced.

  Further, a line connecting the outer peripheral end 14 of the front edge, the first straight line portion, and the contact point 15 of the second R portion is a normal line at the first straight line portion of the second R portion 10 and the contact point 15 of the second R portion. Thus, in the region inside the bell mouth 6 from the first straight line portion of the second R portion 10 and the contact 15 of the second R portion, the sound generated on the pressure surface of the outer peripheral end 14 of the front edge is reflected by the second R portion 10. Then, the sound reflected toward the pressure surface of the blade 4 and reflected by the pressure surface of the blade 4 is emitted to the blowing side. All of the sound that is generated on the pressure surface of the outer peripheral end 14 of the front edge and reflected by the second R portion 10 is released to the blowing side, and the front sound can be reduced.

  The blower including the bell mouth and the propeller fan according to the present invention is useful as a ventilation fan that is used indoors and ventilates because low noise is possible while maintaining the blowing performance.

DESCRIPTION OF SYMBOLS 1 Blower 2 Rotating shaft 3 Leading edge 4 Wing 5 Propeller fan 6 Bell mouth 7 Air flow 8 1st R part 9 1st linear part 10 2nd R part 11 2nd linear part 12 Surface perpendicular | vertical to a rotating axis 13 Angle A
14 Front edge outer peripheral edge 15 Contact point between first straight part and second R part 16 Corner B
17 Side airflow 18 First radiated sound 19 First reflected sound 20 Second radiated sound 21 Second reflected sound 22 First straight line extension line 23 Reflection angle 24 Reflected sound extension line 25 Corner C

Claims (4)

A propeller fan body having a plurality of wings whose front edge is advanced in the direction of rotation, rotating around the rotation axis, and a bell mouth surrounding the outer periphery of the propeller fan,
The bell mouth is
In the shape of a cross section cut by a plane including the rotation axis,
From the suction side to the outlet side end, it has a first R part, a first straight part, a second R part, and a second straight part,
The first R part is
The maximum distance from the rotation axis is Ra, and has a curved shape in which the inside of the bell mouth is concave,
The first straight part is
The side of the small angle formed by the plane that is connected to the first R portion and perpendicular to the rotation axis is the angle A, and is a linear shape that is inclined inward from the outside of the bell mouth to the outlet side,
The second R part is
Connected to the first straight portion, has a curved shape in which the inside of the bell mouth is a convex surface, the second straight portion,
Tangent to the second R portion and linearly parallel to the rotation axis;
The outer diameter Df of the propeller fan and the maximum distance Ra are Ra / Df ≦ 0.85,
The outer angle of the angle formed by the first straight portion and the straight line formed by connecting the outer peripheral end of the front edge of the propeller fan and the contact point of the second R portion and the first straight portion is the angle B,
The angle A and the angle B satisfy an angle A + angle B <90 °. The radius of curvature R1 of the second R portion is
In the ratio with the radial distance Rst2 in the axial direction of the second straight portion,
The blower according to claim 1, wherein R1 / Rst2 ≧ 0.12. The blower according to claim 1 or 2, wherein the center of the radius of curvature of the first R portion is at the outer peripheral end of the leading edge of the blade. The line connecting the contact point between the outer peripheral edge of the blade and the second straight part of the second R part is a normal line at the contact point of the second R part with the second straight part. Item 4. The blower according to any one of Items 1, 2, and 3.

Images