JP2003042094A - Axial flow fan - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an axial flow fan capable of improving sound quality by controlling noise level of offensive high frequency component generated by fan rotation while maintaining a good rotation balance. SOLUTION: In this axial flow fan including a rotating boss part 1 receiving driving force and a plurality of fan blades 2 arranged around the rotating boss part 1, even numbers of same shape fan blades 2 are attached on the rotating boss part 1. Attachment intervals of the fan blades 2 are uneven. The fan blades 2 are provided symmetrically with respect to a center of the rotating boss part 1.

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 cooling a radiator mounted on a vehicle or a condenser of an air conditioner.

[0002]

2. Description of the Related Art As shown in FIG. 3, an axial fan of this type has a rotary boss portion 1 which receives a driving force and a rotary boss portion 1.
In many cases, the fan blades 2 are configured to have a plurality of fan blades 2 arranged around the same, and the respective fan blades 2 have the same shape and are mounted around the rotary boss portion 1 at equal intervals. In such an axial fan, it is known that noise including a large number of rotation order components formed by multiplying a value calculated by the number of blades × rotation speed / 60 by a natural number is generated.

For example, a 6-blade axial fan has 23
When driven at a rotational speed of 75 times, as shown in FIG. 4, the primary component of rotation is 237.5 Hz, the secondary component is 475 Hz, the tertiary component is 712.5 Hz, and the quaternary component is 950 Hz. Will appear.

For this reason, in such an axial fan, the frequency sound of the higher-order component and higher-order components generated by the rotation is audible to the ear, so that the fan blades are spaced unequally in the prior art. It is considered that the rotation order component of noise is dispersed into the nth order component of the blade by setting the above.

[0005]

However, when the intervals between the fan blades are set unevenly, the rotation balance may be deteriorated, and noise of a new specific frequency due to uneven rotation may occur. is there. In addition, the reason why the noise level is projected at a specific frequency when the fan blades are arranged at equal intervals is that the pressure fluctuations of the air generated by the fan blades occur at the same timing, and their components overlap. The reason why the intervals of the fan blades are made unequal to be dispersed in the n-th order component of the blades is to shift the timing of pressure fluctuation caused by the fan blades, but the intervals of the fan blades are made unequal while maintaining the rotational balance. Even in such a case, it is preferable in order to reduce noise that the dispersed wave components do not overlap as much as possible.

In view of the above, the present invention provides an axial-flow fan capable of suppressing the noise of a high-frequency component that is offensive to the ear due to the rotation of the fan while maintaining a good rotational balance to improve the sound quality. That is the issue.

[0007]

In order to achieve the above object, an axial fan according to the present invention comprises a rotary boss portion which receives a driving force, and a plurality of fan blades arranged around the rotary boss portion. The plurality of fan blades are formed of even number fan blades of the same shape attached to the rotation boss portion, and the fan blades are mounted at unequal intervals, and the plurality of fan blades are It is characterized in that they are arranged so as to be point-symmetric with respect to the rotation boss portion (claim 1).

Therefore, an even number of fan blades are
Since the mounting intervals are set to be unequal, they are arranged so as to be point-symmetric with respect to the rotation boss portion.
As shown in FIG. 2, it is possible to reduce the overall noise level as compared with the conventional axial fan shown in FIG. Further, it becomes possible to match the center of gravity of the entire axial fan with the center of the rotating boss portion.

Here, the mounting interval of the fan blades is such that the angle in the circumferential direction is 180 ° divided into a plurality of relatively prime angles, or 180 ° has a greatest common divisor of a predetermined value or less. It is preferable that the intervals are divided into angles (claims 2 and 3). In order to effectively disperse the rotational frequency component while reducing the overlap of the dispersed wave components, it is preferable that the greatest common denominator of the mounting interval (angle in the circumferential direction) is as small as possible. When setting the mounting interval, set the mounting interval to 30
Repeated °, 60 °, 90 ° (maximum common divisor is 30 °)
The installation interval is 50, compared to the case where 40 ° C, 60 ° and 80 ° are repeated (maximum common divisor is 20 °).
Repeated °, 60 °, 70 ° (maximum common divisor is 10 °)
With this, dispersed wave components are less likely to overlap. In other words, it is possible to prevent the frequency components of the entire noise level from being dispersed and the noise level of the specific frequency from increasing as the greatest common divisor of the fan blade mounting interval becomes smaller.

Further, in order to suppress the shake of each fan blade to ensure smooth rotation and maintain the fan strength, it is preferable to connect the outer peripheral ends of the respective fan blades with an annular band (claim 4).

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, an axial fan includes a rotating boss portion 1 fixed to a shaft of a motor (not shown) and receiving a driving force, and six fan blades 2 arranged around the rotating boss portion 1.
And an annular band 3 concentric with the rotary boss 1 connected to the outer peripheral ends of these fan fan blades.

The six fan blades 2 are formed in the same shape, and the fan blades are mounted at intervals of 5 in the circumferential direction.
The intervals are set to 0 ° → 60 ° → 70 ° → 50 ° → 60 ° → 70 °, and the mounting intervals are set as unequal intervals as a whole, and a plurality of fan blades 2 are point-symmetrical about the rotating boss 1 It is arranged so that Therefore, the distance between the adjacent fan blades 2 is
The greatest common divisor is set to 10 °.

Here, each fan blade 2 is
The front edge portion and the rear edge portion are formed in an advancing wing shape having a similar shape to the conventional one, which is formed from the rotary boss portion 1 to the annular band 3 so as to draw a smooth curve without unevenness. In particular, in this example, the straight line A connecting the axial center of the axial fan and the end point of the fan blade 2 on the side of the rotation boss of the blade width center line (indicated by a chain line) and the axial fan axis. The angle connecting the point on the blade width centerline from the center (negative if the point on the blade width centerline is behind the straight line A in the rotation direction, positive if it is on the front side) is from the rotation boss 1 to the middle It becomes negative and changes continuously so as to become positive from the middle to the annular band 3, and the mounting angle gradually decreases from the rotation boss portion 1 to the middle, and gradually increases from the middle to the annular band 3. It is formed in such a shape. The overall diameter of the axial fan is 344
φ and the diameter of the rotary boss portion 1 are set to 137φ.

When the noise level was measured by rotating the axial fan having the above structure, the results shown in FIG. 2 were obtained. This is a noise level of an axial fan (conventional product shown in FIG. 3) in which six fan blades 2 of the same shape are arranged at equal intervals around the rotary boss portion 1 to form the same size (see FIG. 4). (Shown), the rotation order components are dispersed due to the unequal spacing of the fan blades 2.
It was confirmed that the protrusion of high-order components such as third, fourth, and third was alleviated, the noise level could be flattened, and the sound quality was improved. In addition, comparing the noise level of the whole with the noise level of the conventional axial fan,
A reduction effect of dBA or more was confirmed.

Moreover, since the even number of fan blades 2 are arranged so as to be point-symmetric with respect to the rotation boss portion 1, a new peak value of noise due to uneven rotation is also formed. There was no.

In the above construction, the outer peripheral end of each fan blade 2 is connected and fixed to the annular band 3, so that noise caused by vibration of the fan blade 2 can be suppressed. Has become.

Further, in the above-mentioned configuration, the mounting intervals of the fan blades 2 are set by a combination of 50 °, 60 ° and 70 °, and the greatest common divisor of the intervals of the fan blades 2 is set to 10 °. But fan blade 2
As described above, the greatest common denominator of the mounting interval is preferably small, and may be set by a combination of angles in which the angles in the circumferential direction are relatively prime. For example, the fan blades 2 may be arranged point-symmetrically around the rotary boss portion 1 so as to be repeated at intervals of 49 °, 60 °, and 71 °.

Further, in this case, six fan blades 2 are used.
However, the present invention is not limited to this, and even when 8 or more even numbered fan blades 2 are arranged around the rotation boss portion 1, they are point-symmetrical. By arranging them at unequal intervals, it is possible to reduce the noise level of high frequency components without impairing the rotational balance.

[0019]

As described above, according to the present invention,
In an axial fan having a rotary boss receiving a driving force and a plurality of fan blades arranged around the rotary boss, an even number of fan blades having the same shape attached to the rotary boss are provided. Since it is composed of fan blades, the fan blades are installed at unequal intervals, and a plurality of fan blades are arranged so as to be point-symmetrical about the rotation boss portion, so that high frequency components are reduced. It becomes possible to improve the sound quality. Further, since the plurality of fan blades are arranged so as to be point-symmetric with respect to the rotation boss portion, it is possible to eliminate rotation unevenness and maintain good rotation balance.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration example of an axial flow fan according to the present invention.

FIG. 2 is a diagram showing a frequency analysis result of the axial flow fan of the present case.

FIG. 3 is a diagram showing a conventional axial flow fan.

FIG. 4 is a diagram showing a frequency analysis result of a conventional axial flow fan.

[Explanation of symbols]

1 rotating boss 2 fan blades 3 ring band

Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) F04D 29/66 F04D 29/66 M F24F 1/00 316 F24F 1/00 316 (72) Inventor Toshio Tsubakita Osato-gun, Saitama Prefecture Konan Town, Oita 39, Toyo, Higashihara, Zexel Valeo Climate Control Co., Ltd. (72) Inventor, Kentaro Ito 39, Tonan, Konan-cho, Osa-gun, Osa-gun, Chiba, X-Cell Valeo Climate Control Co., Ltd. F-term (reference) 3H033 AA02 AA15 AA18 BB02 BB08 CC01 DD06 DD10 DD17 DD27 EE06 EE08 EE10 3H035 CC02 CC03 CC07 3L011 BF00 3L049 BB07 BC01 BC02 BD03

Claims (4)

[Claims] 1. An axial fan having a rotary boss portion receiving a driving force and a plurality of fan blades arranged around the rotary boss portion, wherein the plurality of fan blades are attached to the rotary boss portion. Consisting of an even number of fan blades of the same shape, with the fan blades mounted at unequal intervals,
An axial fan, wherein the plurality of fan blades are arranged so as to be point-symmetrical about the rotation boss portion. 2. The axial fan according to claim 1, wherein the mounting interval of the fan blades is such that a circumferential angle is 180 ° divided into a plurality of mutually prime angles. 3. The fan blade mounting interval according to claim 1, wherein an angle in a circumferential direction is 180 ° divided into a plurality of angles having a greatest common divisor of a predetermined value or less. Axial fan. 4. The axial fan according to claim 1, wherein each of the plurality of fan blades has an outer peripheral end portion connected to an annular band.