JPH02173395A - Axial flow fan - Google Patents

Abstract

PURPOSE:To enable reduction of the generation of noise and to reduce the consumption power of an electric motor by a method wherein the whole of blade surface is bent three-dimensionally, a ratio between the overall height of a fan and the diameter of the fan and a ratio between the inner size of the fan on the discharge side and the diameter of the fan are set to respective values within a specified range. CONSTITUTION:A blade surface is three-dimensionally bent through the whole thereof, and the sectional shape, extending along a radial direction, of a blade 12 is bent in a manner to protrude toward the suction side. Air flowing in from the suction side along with rotation is boosted on a blade surface. Thus, blast noise generated from the rear edge of an axial flow fan 12 is reduced. A discharge airflow of an axial flow fan 10 at a discharge port 6 is always held approximately at 1600m<8>/h and is set to a value being within a range of H/D0=0.25-0.3, wherein D0 is a fan diameter, and H is the overall height of a fan. By setting a ratio between the inner and the outer sizes of a fan to a value within a range of D1/D0=0.35-0.45 in addition to the above fundamental condition, the generation of blast noise is lowered and the consumption power of an electric motor 9 may be reduced a low value.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Field of Application) The present invention relates to a blower, for example, in an outdoor unit of an air conditioner, in which a heat exchanger is disposed on the suction side and blows out heat-exchanged air to the outside. In particular, the present invention relates to improvements in the axial fan structure that constitutes the fan.

(Prior Art) For example, an outdoor unit of an air conditioner is divided into two parts by a partition plate, and a heat exchanger bent at a substantially right angle in plane is disposed in one chamber. An air blower is disposed so as to face and be separated from this, and the air blower has its fan suction side facing the heat exchanger and its blowing side facing an air outlet provided on the front surface of the unit main body. Its structure consists of an electric motor that is attached and fixed to a pedestal and a fan that is fitted to the rotating shaft of this electric motor.

When selecting the shape and structure of the fan, an axial fan is usually used in order to facilitate the slimming down of the outdoor unit, thereby narrowing the internal space, and to ensure heat exchange efficiency for the heat exchanger.

Conventionally, as shown in FIG. 7, the axial fan has a cylindrical boss hub a that is directly fitted and fixed to the rotating shaft of the electric motor, and a base portion bl that extends along the circumferential surface of the boss hub a.
Blade b, which is a plurality of wings integrally provided with...
The wind flows along the direction of the rotation axis.

(Problem to be solved by the invention) By the way, the outdoor unit of such an air conditioner is literally placed outdoors, and in an environment where it often comes into contact with neighboring houses, making it quiet becomes a big problem. ing. The sound sources that generate noise in the above blower are:
There are only two things: an electric motor and a fan. Although the drive noise level of the electric motor mentioned above is suppressed to a relatively low level,
Since the level of noise generated by the fan's rotational wind is higher than this, various attempts have been made to reduce the noise.

Such a blade b extends from its root part b1 to its peripheral end part b.
It is molded with a so-called "twist" added to it, which curves the entire body three-dimensionally. Moreover, the circumferential end b2 side of the blade b, which is a wing, has a shape that protrudes in the rotational direction to a greater extent than the root part b1 that is integrally provided to the boss hub a. If the blade has a normal shape, that is, both radial edges of the blade are opened symmetrically from the center, the centrifugal force that accompanies rotation causes a so-called boundary layer flow to be blown outward, making the blade thicker. Since the noise level is proportional to the thickness of the boundary layer, it must be made thinner. However, with an axial fan shape like the one shown in the figure, the pressure on the blade surface increases as it moves away from the center of rotation, which helps to suppress the development of the boundary layer and make it thinner. 0 By the way, when the fan diameter of such an axial fan is Do, the fan inner diameter D1 of the trailing edge on the blowing side of blade b is:
That is, since the entire end of the root portion β1 is fixed to the boss hub a, it has the same diameter as the boss hub a itself. Therefore, in such an axial fan, the fan inner/outer diameter ratio D1/Do between the suction side and the blowout side cannot be changed. The above fan diameter ratio is closely related to fluid performance and ventilation noise. Depending on space and other conditions, the relative placement and installation ratio may not necessarily be optimal. If it is done inappropriately, it will naturally lead to problems such as increased power consumption of the electric motor and increased air blowing noise due to decreased fluid performance.

The present invention has been made in view of the above circumstances, and its purpose is to set the ratio within the optimum range based on actual measurements of various fan diameter ratios, ensure a large air volume, and reduce noise. The present invention aims to provide an axial fan structure that consumes less power from an electric motor.

[Structure of the invention]

(Means for Solving the Problems) That is, the present invention is an axial fan in which the root portions of a plurality of blades are integrally provided along the circumferential surface of a cylindrical boss hub, and the blades are The entire surface is three-dimensionally curved, and an inclined boss plate is interposed between the base and the boss hub, and when the fan diameter is Do and the total height of the fan is H, H/D o = 0,
25-0, 3, and the inclined surface boss spray 1
When the inner diameter of the fan at the rear edge on the blow-out side, which is the diameter of the tip of
This is an axial fan structure characterized by being within the range of 45.

(Function) With this configuration, the noise level and the power consumption level of the electric motor are reduced.

(Example) Hereinafter, one embodiment of the present invention will be described based on the drawings.

As shown in FIGS. 1 and 2, an outdoor unit of an air conditioner is constructed. That is, the inside of the unit main body 1 is divided into approximately two parts by the partition plate 2, and the heat exchanger 3 is bent approximately at right angles along the back side and sides of one of the chambers 1a.
is placed.

A blower 4, which will be described later, is arranged so as to face and be away from this. The blower 4 has its fan suction side facing the heat exchanger 3, and its blowing side facing an air outlet 6 covered by a fan guard 5 provided on the front surface of the unit main body 1. In addition, the other chamber 1b partitioned by the partition plate 2 includes a compressor 7. Suction cup 8 etc. are accommodated.

The blower 4 includes an electric motor 9 and a fan 10, and the fan 10 is an axial fan as described below.

That is, the axial fan 10 has a configuration as shown in FIGS. 3 to 5, and has a plurality of blades 12 as wings on the circumferential surface of a cylindrical boss hub 1.
2a... are fixed together with a predetermined interval. More specifically, a plurality of radial ribs 13 are provided on the circumferential surface of the boss hub 11 in a direction perpendicular to the tangent of the boss hub 11, and the tips of each of these radial ribs 13... Aileron ribs 14 are respectively installed in a substantially triangular shape between the boss hub 11 and the circumferential surface thereof.

Then, the inclined surface boss plate 15 is attached so as to close the opening side surface on the suction side formed by the radial rib 13 and the aileron rib 14. The root portion 12a of the blade 12 is
Most of it is integrally fixed to the inclined surface boss spray 1.5, and a portion 12a' projecting from this is directly attached to the circumferential surface of the boss hub 11.

The overall shape of the blade surface of each blade 12 is such that the peripheral end portion 12b thereof protrudes in the direction of rotation. Furthermore, a so-called "twist" that is three-dimensionally curved over the entire wing surface is added, and the blade 12
The cross-sectional shape along the radial direction is curved so as to protrude toward the suction side. Then, as shown in Figure 3, one blade 1
Cutting lines OA to OQ are drawn every 5 degrees from the center point 0 of the blade 12 along the radial direction to the circumferential end 12b, and these cutting lines OA to OQ and the maximum protruding point of the blade 12 protruding toward the suction side. The maximum point curve RR drawn by crossing the maximum point is the curve shown by the two-dot chain line in the figure. This maximum point curve R-R corresponds to the root portion 1.2 of the blade 12.
a, and extends from the leading edge suction side to the trailing edge blowout side.

Here, as shown in Figures 3 and 4, when the fan diameter is DO (mm) and the fan total height is H (+nm), H/D0 is within the range of 0.25 to 0.3. Set it so that On the other hand, the inner diameter of the fan at the rear edge on the Suita side of the blade 12, which is the diameter of the tip of the inclined boss plate 15, is D.
When +(+nm), fan inner/outer diameter ratio is /D.

=0.35-0.45. Preferably, the fan inner and outer diameter ratio is D+ /Do =0.37.
It is preferable to set it within the range of 5 to 0.435.

As shown in FIG. 5, when the boss hub 11 is viewed from the suction side, the central portion of the hub hub 11 is the rotating shaft fitting portion 11. A plurality of boss ribs 16 are installed radially from a to the circumferential surface to ensure sufficient strength.

Next, the operation of the axial fan 10 configured in this manner will be explained. Since the peripheral end portions 12b of the blades 12... protrude to a greater extent in the rotational direction than the root portions 12a, the pressure on the blade surface especially on the outer peripheral side of the blade J2 increases as the distance from the rotation center 0 increases. thus helping to suppress and thin the boundary layer.

In addition, since the blade 12 is shaped to protrude toward the suction side along the radial direction, the centrifugal component of the streamline on the blade surface is reduced, and the component of centrifugal force perpendicular to the blade surface acts as a compressive force. As this rotation occurs, the air flowing in from the suction side increases in pressure on the blade surface. Therefore, it acts to press the boundary layer against the blade surface, suppressing the development of the boundary layer, and particularly reducing the blowing noise generated from the trailing edge of the blade 12.

Furthermore, as particularly shown in FIG. 3, the inflow angle of the streamline on the wing surface of the blade 12 is set to β1. When the outflow angle is β2, from the relationship with the maximum point curve RR, the streamline on the inner circumferential side has a large inflow angle β] and an outflow angle β2, and conversely,
The streamline on the outer circumferential side from the maximum point curve R-R is the inflow angle β]
and the outflow angle β2 becomes smaller. For example, on the inner circumferential side,
When β1-30~40° and β2=40~60°,
On the outer circumferential side, β1 = 25 ~ 15°, β2 - 40 ~
It becomes 25°. In this way, it is possible to greatly change the inflow angle β1 and the outflow angle β2 between the inner circumferential side and the outer circumferential side from the maximum point curves R to R, and the position of the maximum point curve 11-R is close to the root portion 12a. Moreover, since it extends from the leading edge suction side to the trailing edge blowout side, the velocity energy of the wind increases and the pressure increase effect becomes remarkable, especially at and around the root part 12a on the inner peripheral side of this line, and the blowout speed increases. rises and the air volume increases. In other words, a mixed blade effect is achieved in which a centrifugal blade effect is obtained on the inner peripheral side of the blade 12 where the circumferential speed is low, and an axial flow blade effect similar to the conventional one is obtained on the outer peripheral side.

Note that the blower 4 equipped with the axial fan 10 in the outdoor unit configured as described above is driven, and the air volume of the axial fan 10 at the outlet 6 is always maintained at 1600 m3/h.
And the fan diameter is Do (mm), and the fan total height is H (+
nm), H/Do is set within the range of 0.25 to 0.3. In addition to these basic conditions, various fan diameter ratios D + /D o on the outlet side of the blade 12 are prepared.
The level of noise generated and the amount of power consumed by the electric motor at that time were actually measured. The results are shown in Figure 6. As is clear from the figure, the fan inner and outer diameter ratio D+ /Do
=0.35 to 0.45, it has been found that the air blowing noise is reduced and the electric motor 9 consumes less power.

More preferably, the fan inner/outer diameter ratio D, /D.

Better results were obtained when the value was within the range of =0.375 to 0.435.

〔Effect of the invention〕

As explained above, according to the present invention, the entire blade surface is three-dimensionally curved, and the ratio of the fan diameter to the total height of the fan and the ratio of the inner and outer diameters of the fan on the outlet side are set within the optimum range. , the pressure increase effect on the blade surface is ensured to increase the Suita area, and in addition, compared to conventional fans with the same outer diameter, it is possible to achieve much lower noise and reduce the power consumption of the electric motor that drives the fan. This has various effects, such as the ability to improve

[Brief explanation of the drawing]

Fig. 1 is a partially omitted front view of an air conditioner outdoor unit equipped with an axial fan showing an embodiment of the present invention, Fig. 2 is a schematic cross-sectional plan view thereof, and Fig. 3 is a blowout of the axial fan. 4 is a partially omitted vertical cross-sectional view, 5 is a front view of the main part on the suction side, and 6 is a characteristic of noise level and electric motor power consumption level with respect to the ratio of the fan's inner and outer diameters. 7 are front views of an axial fan showing a conventional example of the present invention. 11...Boss hub, 12...Blade, 12a...
- Root part (of the blade), 15... Slanted boss plate. Applicant's Representative Patent Attorney Takehiko Suzue Diagram

Claims (1)

[Claims] This is an axial fan in which the root portion of a plurality of blades, which are blades, are integrally provided along the circumferential surface of a cylindrical boss hub, and the blade has its entire blade surface curved three-dimensionally. A sloped boss plate is interposed between the base portion and the boss hub, and when the fan diameter is D_0 and the total height of the fan is H, H/D_0=0.25 to 0.3, and the above An axial flow characterized by having a fan inner diameter ratio D_1/D_0=0.35 to 0.45, where D_1 is the inner diameter of the fan at the rear edge on the blowout side, which is the diameter of the tip of the inclined boss plate. fan structure.