JP2662125B2 - Axial fan - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an axial fan used for ventilation ventilation equipment and air conditioning equipment.

[0002]

2. Description of the Related Art In recent years, there has been an increasing demand for ventilation and ventilation equipment and air conditioning equipment used in living and non-living spaces to reduce noise.

[0003] Conventionally, in order to reduce the noise of this type of axial fan, a propeller fan having a shape in which a blade surface is advanced in a rotational direction is generally known. Hereinafter, the configuration will be described with reference to FIGS.

As shown in FIG. 1, a propeller fan 103 (shown in FIG. 1) has a plurality of blades 101 mounted on a hub 102.
) Are arranged in the annular ventilation opening 104 having the bell mouth shapes 104a and 104b and the straight pipe portion 104c while maintaining a constant clearance a in the circumferential direction.
The blade 101 has a blade shape in which the center of the chord is advanced in the rotation direction b from the hub mounting portion 101a to the outer peripheral edge 105. Generally, the thickness of the blade 101 in a radial cross section passing through a certain line AA ′ in the radial direction is generally equal to the hub mounting portion 101.
From a, the outer peripheral edge 105 has the same thin shape or a shape in which the thickness gradually decreases toward the outer peripheral edge 105 from the consideration of strength.

[0005] In the above configuration, the general ventilation direction of the air when the propeller fan 103 rotates is as shown by an arrow b 'through the propeller fan 103 .

[0006]

In such a conventional axial flow fan, the air flow on the blade surface becomes centripetal flow c from the leading edge 106 to the trailing edge 107, and the hub mounting portion 1
The flow is such that effective work is performed from 01a toward the outer peripheral edge 105. However, when the distance is very close to the outer peripheral edge 105, the amount of work is suddenly reduced and an effective flow is not obtained. When the wing tip portion 105a of the outer peripheral edge 105 protrudes upstream from the straight pipe portion 104c of the ventilation port 104, the flow of air in the d direction received by the bell mouth shape 104a is not limited to the front edge 106. The wing tip 1
It also flows in from 05a. At this time, in particular, the wing tip 1
In the case of 05a, a vortex f1 due to turbulence in the flow is likely to be generated at the time of the inflow of air, and this vortex f1 is one of the causes of noise.

At the wing tip 105b, a flow from the pressure surface 108 to the suction surface 109 is generated. In particular, a flow e substantially in the direction along the pressure surface 108 is generated by the wing tip 105b and the ventilation direction 104. At the same time as the direction is suddenly changed, and at the same time, the vortex f2 flows to the negative pressure surface 109 with the generation of the vortex f2.
There was one problem.

Here, as a measure for reducing the noise of the propeller fan 103, the straight pipe portion 104c
When the length is set to a sufficient length with respect to the axial width of the blade 101, it is possible to considerably prevent the inflow of turbulent air into the blade tip portion 105a and the vortex sound generated by the inflow. However, in the case of an air-conditioning outdoor unit, it is often not effective to take the straight pipe portion 104c long in consideration of the product configuration and heat exchange performance. In this measure, the wing tip 105
In b, there is a problem that it is not possible to prevent a vortex sound generated when a flow occurs from the pressure surface 108 to the suction surface 109.

In addition to the above, the propeller fan 103
Has a problem that various noises are generated during the rotation operation.

A first object of the present invention is to solve the above-mentioned problems and to prevent generation of the vortex f1 due to turbulence in the flow of air at the wing tip 105a and noise caused by the vortex f1. I do.

A second object is to prevent the vortex f2 generated in the flow of air flowing from the pressure surface 108 to the suction surface 109 at the blade tip portion 105b and noise caused by the vortex f2.

A third object is to provide the vortex f1 and the vortex f
2 and the absolute amount of various noises generated during the rotation operation of the propeller fan 3.

[0013]

According to the present invention, there is provided an axial flow fan, wherein the first means for achieving the first and second objects comprises a plurality of blades on an outer periphery of a hub. A semicircular thick part having a radius of curvature is arranged on a part or the whole of the positive pressure surface on the outer peripheral edge.

The second means has a configuration in which a semicircular thick portion having a radius of curvature is arranged on a part or all of the negative pressure surface on the outer peripheral edge of each blade.

A third means for achieving the third object comprises an auxiliary wing in which a part or all of a trailing edge of each blade is bent toward a pressure side with respect to a surface of the blade. The blade has a configuration in which a part or a plurality of air flow paths formed in a bent portion of the auxiliary wing are arranged.

[0016]

According to the first aspect of the present invention, the turbulent flow flowing into the upstream wing tip of the outer peripheral edge is controlled by the semicircular thick portion provided on the pressure side of the wing tip. Even if it flows in from the direction, it is smoothly received on the pressure side, and vortices and whirl noise can be reduced. Also, in the flow from the pressure surface to the suction surface at the downstream blade end portion of the outer peripheral edge, the thick portion provided on the pressure surface side of the blade end smoothly flows to the suction surface, causing vortices and whirl noise. Can be reduced.

Further, the turbulent flow flowing into the outer peripheral edge upstream wing tip portion is smoothly received by the positive and negative pressure surfaces irrespective of the flow direction from the second means. Is what you can do. Also, in the flow from the pressure surface to the suction surface at the downstream end of the outer peripheral edge, the thick portion is provided on the suction surface side, so that the flow can be further smoothly performed, and vortices and whirl noise can be reduced.

Further, with the configuration of the third means, the pressure and the lift coefficient increase under the same rotation speed as the axial fan of the first or second means, and the air volume increases. Therefore, since the number of revolutions can be reduced in order to make the air volume equal, the absolute amount of noise generation can be reduced.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIG. The same parts as in the conventional example are denoted by the same reference numerals, and detailed description is omitted.

As shown in the drawing, a semicircular thick portion 1 is provided on a positive pressure surface 108 of an outer peripheral edge 105 of a blade 101, and FIG. 10B shows a radial cross section passing through 105 a, and FIG. 10B shows a radial cross section passing through the downstream wing tip 105 b of the outer peripheral edge 105.

With the above configuration, when the blade 101 rotates, the pressure surface 10
The flow d with turbulence flowing into 8 becomes a flow along the thick portion 1 regardless of the flow direction. That is, the flow can be smoothly guided to the positive pressure surface 108 by the thick portion 1. Therefore, generation of the vortex f1 can be reduced, and noise generated by the vortex f1 can be reduced.

Further, the blade 101 has the above-described configuration.
Is generated during the rotation operation from the pressure side to the suction side 109.
The flow e substantially along the pressure surface 108 in the flow toward と な り becomes a flow along the thick portion 1 at the wing tip portion 105b and further becomes a flow nearly perpendicular to the blade 101, It is possible to prevent a sudden change in the direction of flow at the wing tip portion 105b, such as when there is no thick portion 1. Therefore, the vortex f2 generated on the suction surface 109 of the blade tip portion 105b due to the rapid change of the flow direction can be reduced, and the noise generated by the vortex f2 can be reduced.

As described above, according to the axial fan of the first embodiment of the present invention, the vortex f1 generated at the outer peripheral edge 105 by providing the thick portion 1 on the pressure surface 108 of the outer peripheral edge 105. And f2, this vortex f1
And f2 noise can be reduced.

Next, a second embodiment of the present invention will be described with reference to FIG. The same parts as in the conventional example are denoted by the same reference numerals, and detailed description is omitted.

FIG. 2 shows the configuration of FIG.
The thickness of the semi-circular thick portion 2 is provided on the negative thick surface 109 of the reference numeral 05.

With the above configuration, when the blade 101 rotates, the pressure surface 10
8 and the turbulent flow d flowing into the negative thick surface 109 are flow along the thick portions 1 and 2 regardless of the flow direction. That is, the thick portion 1 and the thick portion 2 can smoothly guide the flow to the pressure surface 108 and the suction surface 109. Therefore, the generation of the vortex f1 can be reduced more than in the first embodiment.
It can be reduced as described above.

Further, with the above configuration, the blade 101
Is generated during the rotation operation from the pressure side to the suction side 109.
The flow e substantially along the pressure surface 108 in the flow toward, becomes a flow along the thick portion 1 at the wing tip portion 105b, and further becomes a flow nearly perpendicular to the blade 101. Then, the flow smoothly moves along the thick portion 2 and smoothly flows into the negative pressure surface 109. Therefore, it is possible to prevent a sudden change in the flow direction at the wing tip portion 105b, which is caused when the thick portion 1 and the thick portion 2 are not provided, as compared with the first embodiment. Therefore, the abrupt change in the direction of the flow causes the wing tip 1
The vortex f2 generated on the negative pressure surface 109 in the area 05b can be reduced, and the noise generated by the vortex f2 can be reduced more than in the first embodiment.

As described above, according to the axial fan of the second embodiment of the present invention, the thick portion 1 and the thick portion 2 are provided on the positive pressure surface 108 and the negative pressure surface 109 of the outer peripheral edge 105.
Is provided, the vortices f1 and f2 generated at the outer peripheral edge 105 and the noise due to the vortices f1 and f2 can be reduced more than in the first embodiment.

As a result of examining a change in noise when the thickness of the thick portions 1 and 2 is changed, the radial length and the radius of curvature of the thick portions 1 and 2 are shown in FIG. from the outer diameter D ₁ of the fan by pulling the outer diameter D ₂ of the hub with respect to the distance D ₃ divided by 2, the radial length of 2% to 6%
And the radius of curvature is in the range of 1% to 3%.

Next, a third embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIGS. The same parts as in the conventional example are denoted by the same reference numerals, and detailed description is omitted.

FIG. 4 is a front view of the blade 101 of the second embodiment as viewed from the downstream side. The auxiliary wing 3, the bent portion 4, and the air flow passage 5 in the bent portion 4 are formed at a plurality of positions, for example, at three positions. It has a configuration provided in places. FIG.
FIG. 4 shows a circumferential cross section taken along line DD ′ passing through the air flow path portion 5 in the circumferential direction of the blade 101 of the embodiment;
The trailing edge 107 of the blade 101 is
The auxiliary wing 3 is formed at an angle α to the pressure surface 108 side of the auxiliary wing 1 so that air flowing along the pressure surface 108 flows out smoothly without changing the angle.
The air passage section 5 is provided in the bent section 4 of FIG. FIG. 6A shows a line EE which does not pass through the air flow path 5 in the circumferential direction of the blade 101 of the second embodiment.
2 shows a cross section in the circumferential direction. The dashed line (b) is a circumferential cross section near the trailing edge along the line EE in the case of the conventional blade 101 without the bent portion 4 and the auxiliary wing 3.

With the above configuration, in FIG.
When the blade 101 is rotating at the peripheral speed u, the absolute speed c
₁(Hereinafter c)₁) Is the flow of the leading edge 106
Inflow relative velocity w along the pressure surface 108₁(Below, before
Note w₁). And the rear edge 107
Outflow relative velocity w along the pressure surface 108_Two(Below, before
Note w_Two), And is stopped by the resultant force with the peripheral speed u.
Speed c_Two(Hereinafter c) _TwoAnd c) is obtained._TwoLap of
The direction component is the absolute circumferential speed c._2uAnd In addition, the w₁
And the w_TwoHalf of the resultant force is the average relative speed w_Three(Hereinafter, the above
w_Three). FIG. 6B also shows
Similarly, various speeds can be obtained. here,
In general, the equation for pressure is:

[0033]

(Equation 1)

[0034]

(Equation 2)

Where P is pressure, g is gravitational acceleration,
γ is specific weight, l is chord length, t is inter-blade distance and C_LHaage
Represents the force coefficient. As is apparent from FIG.
If they are equal, it is better to have the aileron 3
3 compared to the case without 3 _2uIs large (Equation 1)
Increases the pressure. Thinking this in connection with (Equation 2)
When you get_ThreeIs better when the auxiliary wing 3 is provided.
As it is smaller than without the aileron 3,
Number C_LWill increase. Therefore, under the same rotation speed
Means that having the auxiliary wings 3 increases the air volume.
You. Therefore, the air volume without the auxiliary wing 3 and
When the rotation speed is not provided with the auxiliary wing 3 for equalization
Absolute noise generation at the same time as it can be reduced
Can be reduced.

Further, according to FIG.
In the bent portion 4 of 09, the flow flowing through the negative pressure surface is separated, and a vortex is likely to be generated, which may cause stall and noise. The flow can dissipate vortices and prevent stalls and noise.

As described above, according to the axial fan of the third embodiment of the present invention, the use of the auxiliary wings 3 having the bent portion 4 and the air passage portion 5 reduces the absolute amount of noise generation. Can be reduced.

[0038]

As is clear from the above embodiments, according to the present invention, an axial fan having an effect of particularly reducing vortex noise among fluid noises generated from the axial fan can be provided.

In addition, it is possible to provide an axial fan having an effect of reducing the absolute amount of noise by reducing the number of revolutions under the same air flow.

[Brief description of the drawings]

FIG. 1A is a sectional side view of a main part of an upstream blade tip of an axial flow fan according to a first embodiment of the present invention; FIG.

FIG. 2A is a sectional side view of the second embodiment; FIG. 2B is a sectional side view of the second embodiment;

FIG. 3 is a front view of the same.

FIG. 4 is a front view of the third embodiment.

FIG. 5 is a side sectional view of the same.

6A is a cross-sectional view of the EE in the circumferential direction of FIG. 4;

FIG. 7 is a front view of a conventional axial fan.

FIG. 8 is a side view of the same.

FIG. 9 is a sectional side view of the main part.

FIG. 10 is a side sectional view of the main part.

FIG. 11 is a sectional side view of the main part.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Thick part 2 Thick part 3 Auxiliary wing 4 Bent part 5 Air flow path 101 Blade 105a Upstream wing end 105b Downstream wing end 106 Front edge 107 Trailing edge 108 Pressure side 109 Pressure side

Claims (3)

(57) [Claims] An axial flow comprising a plurality of blades provided on an outer periphery of a hub, and a semicircular thick portion having a radius of curvature is arranged on a part or all of a pressure surface on an outer peripheral edge of each of the blades. fan. 2. The axial flow fan according to claim 1, wherein a semicircular thick portion having a radius of curvature is disposed on a part or all of the negative pressure surface on the outer peripheral edge of each blade. 3. An air flow path formed in a bent portion of the auxiliary wing of the blade, the auxiliary blade having a part or the whole of a trailing edge of each blade bent toward the pressure side with respect to the surface of the blade. 3. The axial flow fan according to claim 1, wherein a part or a plurality of parts are arranged.