JP7069406B2 - Propeller fan and blower - Google Patents

Description

The present invention relates to a propeller fan and a blower in which a plurality of sheet metal blades are provided around a boss portion.

The blower exemplified for the air conditioner and the ventilation fan may use a propeller fan having a plurality of blades around the boss portion. The propeller fan rotates the boss portion and the blade to flow air in the direction along the rotation axis and blow it.

Propeller fans are required to reduce noise during rotation. Patent Document 1 discloses a configuration in which the leading edge of a propeller fan blade is provided with a flap whose leading edge is tilted toward the positive pressure surface to aim at rectification of the airflow flowing into the blade and reduce noise. ing.

Japanese Unexamined Patent Publication No. 8-177792

The propeller fan may be used for a blower in which the propeller fan is surrounded by a duct. When the duct surrounds the entire area along the rotation axis of the propeller fan, the flap induces the separation of the air flow due to the inflow angle of the air to the leading edge of the propeller fan, which worsens the noise. It may end up.

The present invention has been made in view of the above, and an object of the present invention is to obtain a propeller fan capable of reducing noise even if the surroundings are covered with a duct.

In order to solve the above-mentioned problems and achieve the object, the propeller fan according to the present invention has a boss portion that rotates around a rotation axis, and a boss portion that is provided around the boss portion and rotates together with the boss portion in a rotation direction. A blade having a positive pressure surface facing forward and a negative pressure surface facing backward in the rotation direction, and a protruding portion having a front edge portion which is a front edge in the rotation direction of the blade projecting toward the negative pressure surface side.

The propeller fan according to the present invention has an effect that noise can be reduced even if the surrounding area is covered with a duct.

Front view of the blower device according to the first embodiment of the present invention. Cross-sectional view of the blower cut by the line II-II shown in FIG. Sectional drawing of the blade cut along the line III-III shown in FIG. The figure which shows the relationship between the protrusion ratio and noise difference in the blower device which concerns on Embodiment 1. The figure which shows the relationship between the range which provided the protruding part in the blower device which concerns on Embodiment 1 and a noise difference. The figure which shows the modification of the blower device which concerns on Embodiment 1. It is sectional drawing of the blower device which concerns on a comparative example, and corresponds to the sectional view shown in FIG. It is sectional drawing of the propeller fan which concerns on a comparative example, and corresponds to the sectional view shown in FIG.

Hereinafter, the propeller fan and the blower according to the embodiment of the present invention will be described in detail with reference to the drawings. The present invention is not limited to this embodiment.

Embodiment 1.
FIG. 1 is a front view of the blower device according to the first embodiment of the present invention. FIG. 2 is a cross-sectional view of the blower cut along the line II-II shown in FIG. The blower 30 includes a propeller fan 10 and a duct 4. The propeller fan 10 includes a boss portion 2 and a blade 1.

The boss portion 2 and the blade 1 receive a driving force from a motor 5 which is a driving source, and rotate about a rotation shaft 3. The blade 1 is provided around the boss portion 2 and rotates together with the boss portion 2. The rotation directions of the boss portion 2 and the blade 1 are indicated by arrows X. When the blade 1 rotates, an air flow 6 is generated. The motor 5 is arranged on the downstream side in the flow direction of the air flow 6 with respect to the propeller fan 10. In the following description, the direction along the rotation axis 3 is simply referred to as an axial direction. Further, the radial direction of the circle centered on the rotation axis 3 is simply referred to as the radial direction. Further, the circumferential direction of the circle centered on the rotation axis 3 is simply referred to as the circumferential direction.

FIG. 3 is a cross-sectional view of the blade cut along line III-III shown in FIG. The cross-sectional view shown in FIG. 3 can be rephrased as a cross-sectional view of the blade 1 viewed along the radial direction. The blade 1 is provided with an inclination with respect to the rotation direction, and has a positive pressure surface 1a which is a surface facing forward in the rotation direction and a negative pressure surface 1b which is a surface facing backward in the rotation direction. A protruding portion 13 protruding toward the negative pressure surface 1b is provided from the leading edge portion 11 which is the front edge in the rotation direction of the blade 1. The trailing edge of the blade 1 in the rotation direction is the trailing edge portion 12.

The distance between the tip 13a of the protruding portion 13 and the tangent line 14 in the perpendicular direction with respect to the tangent line 14 of the positive pressure surface 1a at the leading edge portion 11 when the protrusion amount H of the protruding portion 13 shown in FIG. 3 is viewed along the radial direction. Is defined as. Further, the length of the blade 1 along the circumferential direction at the blade center radius _rma shown in FIG. 1 is defined as the chord length _cm . Further, a protrusion ratio α in which the protrusion amount H is made dimensionless by the chord length _cm is defined. The protrusion amount H is positive when the protruding portion 13 protrudes to the negative pressure surface 1b side, and negative when the protruding portion 13 protrudes to the positive pressure surface 1a side. Specifically, it is defined as α = H / _cm . The protrusion ratio α has the same value in any of the cross sections of the blade 1 cut along the arc centered on the rotation axis 3.

Lines III-III shown in FIG. 1 are arcs having a blade center radius r _ma centered on the rotation axis 3. The blade center radius r _ma is defined by r _ma = (r1 + r2) / 2 when the radius of the outer peripheral edge 15 of the blade 1 is r1 and the radius of the inner circumference of the blade 1, that is, the radius of the boss portion 2 is r2. Radius.

As shown in FIG. 1, the duct 4 is a cylindrical body that surrounds the propeller fan 10 when viewed along the rotation axis 3. As shown in FIG. 2, the duct 4 extends from the downstream side to the upstream side of the blade 1 in the direction of the air flow 6 generated by the rotation of the blade 1 when viewed from the direction perpendicular to the rotation axis 3. Surrounds the area. That is, the entire blade 1 from the upstream end to the downstream end is surrounded by the duct 4.

This configuration can also be explained as follows. That is, the end surface 4a of the duct 4 on the downstream side in the direction of the air flow 6 is defined as a reference. Let B be the distance from the reference to the blade trailing edge wing tip 12a. Let A be the distance from the reference to the blade leading edge blade tip 11a. Let C be the duct height from the standard. The relationship between the propeller fan 10 and the installed state of the duct 4 satisfies the relationship of 0 ≦ B <A and B <A ≦ C.

FIG. 3 shows the flow field and the inflow angle θ of the airflow 6 when the blade 1 rotates. When the blade 1 rotates, there is an air flow 6 that flows into the leading edge portion 11 of the blade 1. In the blower device 30, since the periphery of the propeller fan 10 is covered with the duct 4, the airflow 6 flowing into the leading edge portion 11 of the blade 1 has a strong component that travels in the extending direction of the duct 4, that is, in the axial direction. The inflow angle θ becomes close to 90 deg, and the air flow 6 flows into the leading edge portion 11 of the blade 1 at an angle slightly perpendicular to the negative pressure surface 1b.

In order to reduce the noise generated when the propeller fan 10 rotates, it is effective to suppress the peeling region where the airflow is separated. As shown in FIG. 3, by providing the projecting portion 13 projecting to the negative pressure surface 1b side, a flow along the air flow 6 is formed, so that it is possible to suppress the peeling region and reduce noise.

FIG. 4 is a diagram showing the relationship between the protrusion ratio and the noise difference in the blower according to the first embodiment. FIG. 4 shows the relationship between the protrusion ratio α and the noise difference under the condition that the protruding portion 13 is provided within the range of r2 to 0.7 × r1. FIG. 5 is a diagram showing the relationship between the range in which the protruding portion is provided and the noise difference in the blower according to the first embodiment.

The vertical axis shown in FIG. 4 shows the difference from the noise at the same air volume when the protruding portion 13 is not provided on the blade 1. It is shown that the noise difference becomes positive when the noise is larger than the noise when the protruding portion 13 is not provided on the blade 1. It is shown that the noise difference becomes negative when the noise is smaller than the noise when the protruding portion 13 is not provided on the blade 1. If the protruding portion 13 is not provided, α = 0 and the noise difference is 0. Further, the horizontal axis shown in FIG. 4 indicates the protrusion ratio α. Further, in FIG. 4, the points where the results of measuring the noise difference with different protrusion ratios α are plotted are shown by connecting them with a straight line.

From the results shown in FIG. 4, when the protrusion amount H = α × _cm of the protruding portion 13 is defined, there is a low noise effect in the range of 0 <α <0.029, and among them, 0.007 <α <0. In the range of .027, there is an effect of −0.3 dB, and in the range of α = 0.015, it is −0.6 dB, which is the lowest noise effect.

As shown in FIG. 4, there is a protrusion ratio α in which the noise difference becomes positive and the improvement effect cannot be obtained. It is considered that the reason for this is that in the range of the protrusion ratio α where the noise difference is positive, the protruding portion 13 does not follow the air flow 6, and the peeling region formed on the negative pressure surface 1b becomes large, which causes an increase in noise. Be done.

In FIG. 5, the protrusion amount H of the protrusion 13 is projected to the leading edge portion 11 under the condition that the protrusion amount H of the protrusion 13 is fixed at H = α × _cm = _0.0145 × cm where the noise improvement effect can be confirmed most in FIG. The relationship between the range in which the portion 13 is provided and the low noise effect value is shown.

The vertical axis shown in FIG. 5 shows the difference from the noise at the same air volume when the blade 1 is not provided with the protruding portion 13. When the noise is larger than the noise when the blade 1 is not provided with the protruding portion 13, the noise difference becomes positive. When the noise is smaller than the noise when the blade 1 is not provided with the protruding portion 13, the noise difference becomes negative.

Further, the horizontal axis shown in FIG. 5 indicates a range in which the protruding portion 13 of the leading edge portion 11 is provided from the radius r2 of the boss portion 2 toward the outer peripheral edge 15 of the blade 1, and the range thereof is the outer peripheral edge of the blade 1. It is shown as a ratio of 15 to the radius r1.

From the results shown in FIG. 5, when the projecting portion 13 is provided in the range from the outer peripheral surface of the boss portion 2 which is the root of the blade 1 to r _ma , r _ma is 0.6 × r1 ≦ r _ma <0.8 ×. There is an effect of reducing noise in the range of r1. Among them, there is the lowest noise effect of −0.5 to −0.6 dB in the range of 0.6 × r1 ≦ r _ma ≦ 0.7 × r1.

On the other hand, when r _ma is in the range of 0.8 × r1 <r _ma , it can be seen that the noise is exacerbated. The reason why the noise is exacerbated is that the relative flow velocity of the inflowing airflow 6 is larger in the outer periphery of the blade 1 than in the portion having a small radius, so that the protruding portion 13 does not follow the airflow 6 and is located on the outer periphery of the blade 1. It is probable that it caused the disturbance of.

By providing the protruding portion 13 on the leading edge portion 11 of the blade 1, the section modulus of the blade 1 is increased, so that the stress generated at the root portion of the blade 1 during the rotation of the propeller fan 10 is reduced. That is, the strength and proof stress of the propeller fan 10 can be improved.

As described above, it is possible to provide the propeller fan 10 which has the effects of reducing noise and improving strength and proof stress without causing a decrease in air volume. Further, the blower device 30 using the propeller fan 10 is, for example, an air conditioner, a ventilation fan, a fan, or a circulator.

FIG. 6 is a diagram showing a modified example of the blower device according to the first embodiment. Even in the blower device 30 according to the modified example, the relationship between the installed state of the propeller fan 10 and the duct 4 satisfies the relationship of 0 ≦ B <A and B <A ≦ C. In the blower device 30 according to the modified example, the cross-sectional area of the duct 4 does not change in the axial direction. Even in the blower device 30 provided with such a duct 4, it is possible to provide the propeller fan 10 which has the effects of reducing noise and improving strength and proof stress without causing a decrease in air volume.

FIG. 7 is a cross-sectional view of the blower device according to the comparative example, and is a view corresponding to the cross-sectional view shown in FIG. FIG. 8 is a cross-sectional view of the propeller fan according to the comparative example, and is a view corresponding to the cross-sectional view shown in FIG.

In the blower device 40 according to the comparative example, the duct 41 is directed from the upstream side to the further upstream side of the blade leading edge wing tip 11a of the blade 1 in the direction of the air flow 6 when viewed from the direction perpendicular to the rotation axis 3. It extends and surrounds the blade 1. That is, the upstream portion of the blade 1 is not surrounded by the duct 41. In this configuration, the relationship between the installed state of the propeller fan 10 and the duct 41 satisfies the relationship of 0 ≦ B <C <A.

In this case, as shown in FIG. 8, the airflow 6 flowing into the leading edge portion 11 of the blade 1 has a strong component traveling in the circumferential direction because the upstream side is not surrounded by the duct 4, and the inflow angle θ is 0 deg. The airflow 6 flows horizontally into the leading edge portion 11 of the blade 1. When the airflow 6 flows horizontally into the leading edge portion 11 of the blade 1, a protruding portion 13 protruding toward the negative pressure surface 1b is provided like the propeller fan 10 according to the first embodiment. On the contrary, the airflow may separate on the negative pressure surface 1b side and the noise may worsen.

The configuration shown in the above embodiments shows an example of the contents of the present invention, can be combined with another known technique, and is one of the configurations as long as it does not deviate from the gist of the present invention. It is also possible to omit or change the part.

1 blade, 1a positive pressure surface, 1b negative pressure surface, 2 boss part, 3 rotation shaft, 4,41 duct, 5 motor, 6 airflow, 10 propeller fan, 11 leading edge, 11a blade leading edge wing tip, 12 trailing edge. Part, 12a blade trailing edge wing tip, 13 overhang, 13a tip, 14 tangent, 15 outer edge, 30,40 blower.

Claims (4)

The boss that rotates around the axis of rotation and
A blade provided around the boss portion, which rotates together with the boss portion and has a positive pressure surface facing forward in the rotation direction and a negative pressure surface facing backward in the rotation direction.
A part of the leading edge portion, which is the front edge in the rotation direction of the blade, is provided with a protruding portion that protrudes further forward than the leading edge portion and protrudes toward the negative pressure surface side.
The boss portion has a cylindrical shape centered on the rotation axis.
When the radius of the boss portion is r2 and the outer peripheral radius of the blade is r1, the protruding portion is provided in the range of r2 to 0.7 × r1.
The distance between the tip of the protruding portion and the tangent line and the protrusion amount H of the protruding portion in the perpendicular direction with respect to the tangent line of the positive pressure surface at the leading edge portion when viewed along the radial direction centered on the rotation axis. Defined as
The center radius r _ma of the propeller fan of the blade is set to r _ma = (r1 + r2) / 2.
Let _cm be the chord length, which is the length of the blade along the circumferential direction in the central radius.
When the protrusion ratio α is defined as α = H / _cm ,
A propeller fan characterized by satisfying 0 <α <0.029 . The propeller fan according to claim 1 , wherein 0.007 ≤ α ≤ 0.027 is satisfied. The propeller fan according to claim 1 , wherein α = 0.015. The propeller fan according to any one of claims 1 to 3 .
Further provided with a cylindrical duct that surrounds the propeller fan as viewed along the axis of rotation.
The duct has a region extending from the downstream side to the upstream side of the blade and surrounding the blade in the direction of the air flow generated by the rotation of the blade when viewed from a direction perpendicular to the rotation axis. A blower that features.

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