JPH06129387A - Lateral flow fan - Google Patents

Abstract

PURPOSE:To reduce the noise level by installing vanes in circular arc on an impeller in circumferential arrangement at random pitch angles, installing a plurality of such impellers along the rotary shaft, and dislocating the impeller at a certain angular pitch in the circumferential direction. CONSTITUTION:A lateral flow fan is equipped with an impeller 2 which has vanes 1 in the form of circular arc curving forward, wherein the vanes 1 are arranged in the circumferential direction at random pitch angles 1, 2, 3..., and a plurality of such impellers 2 are provided along the rotary shaft in such an arrangement as dislocated at 1-4deg. intervals in the circumferential direction. This permits reducing peak noises without impairing the blowing characteristic and achieving a lateral flow fan with the noise reduced to a great extent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cross flow fan used in an air conditioner and the like, and more particularly to a cross flow fan capable of reducing noise level.

[0002]

2. Description of the Related Art Conventionally, as a cross-flow fan of this type, as shown in FIG. 3, arc blades 31, 31, ... Of an impeller 30 are arranged at equal pitch angles β, β ... And shown in FIG. As described above, there is a configuration in which a plurality of impellers 30 are arranged in a zigzag pattern in the rotation axis direction so that the arcuate blades 31 of every other impeller 30 in the rotation axis direction have the same phase in the circumferential direction.

[0003]

However, in the above-mentioned conventional cross-flow fan, the NZ sound which is the sound of the frequency of the product NZ of the fan rotation speed N per second and the number Z of arc blades,
There is a problem in that the 2NZ sound, which is a sound having a frequency of 2NZ that is twice the product NZ, becomes significantly louder than sounds of other frequencies, and noise that is audible to the ear is generated. An example of this phenomenon is shown in the sound frequency spectrum of FIG. Further, there is a problem that the above phenomenon becomes a factor of increasing the A-scale sound as the total sound.

Therefore, an object of the present invention is to provide a cross flow fan capable of reducing the noise level.

[0005]

To achieve the above object, a cross-flow fan of the present invention is a cross-flow fan including an impeller having a plurality of forwardly curved arc blades, wherein the arc blades of the impeller are randomly arranged. A plurality of impellers are arranged in the circumferential direction at a pitch angle, a plurality of the impellers are arranged in the rotation axis direction, and the plurality of impellers are displaced by 1 ° to 4 ° in the circumferential direction. .

[0006]

According to the above structure, as shown in FIG. 5 (A) in which the horizontal axis represents the air volume and the vertical axis represents the sound pressure levels of the NZ sound and the 2NZ sound, as shown in FIG. Compared with the sound pressure level of the 2NZ sound of the conventional example shown by the characteristic (a) connected by the broken line, the sound pressure level of the 2NZ sound of the crossflow fan of the present invention shown by the characteristic (ii) connected by the broken line is significantly large. Decreased to.

Similarly, as shown in FIG. 5 (A), compared with the sound pressure level of the NZ sound of the conventional example shown by the characteristic (U) in which the Δ mark is connected by the solid line, the characteristic in which the ◯ mark is connected by the solid line is shown. The sound pressure level of the NZ sound of the cross flow fan of the present invention shown by (E) is reduced.

Further, as shown in FIG. 5 (B), compared with the sound pressure level of the blast sound of the conventional example shown by the characteristic (o) represented by the triangle mark and the solid line, the characteristic (or) represented by the circle mark and the solid line. Shows that the sound pressure level of the blowing noise of the cross flow fan of the present invention is reduced.

Further, even when the pitch angles between the arc blades of the impeller are randomly arranged, a plurality of impellers are circumferentially arranged at 1 °.
In the cross-flow fan having a skew angle of 34 °, which is displaced by 34 ° in the circumferential direction without being displaced by 4 ° in FIG.
A peak sound is generated as shown in the sound frequency spectrum of (B). In addition, in a cross-flow fan having a skew angle of 36 ° in which a plurality of impellers are displaced by 36 ° in the circumferential direction,
As shown in (C), many peak sounds were generated. Furthermore, although not shown in the figure, a peak sound of 2NZ sound was generated even in the cross-flow fan having a skew angle of 5 °.

On the other hand, a plurality of impellers are arranged at 2 ° in the circumferential direction.
According to the cross-flow fan having a skew angle of 2 ° according to the present invention, which is displaced from each other, as shown in FIG. 8 (A), FIG.
It was possible to eliminate the peak sound shown in (C).

[0011]

The present invention will be described in detail below with reference to the embodiments shown in the drawings.

As shown in FIG. 1, the cross flow fan of this embodiment is provided with an impeller 2 having a plurality of forwardly curved arc blades 1, 1, ... The pitch angles α1, α2, α3 ... Are arranged in the circumferential direction.

As shown in FIG. 2, a plurality of the impellers 2 are arranged in the direction of the rotation axis, and the plurality of impellers 2, 2 ... Are displaced by 1 ° to 4 ° in the circumferential direction. ing.

FIG. 5 shows the result of the comparative noise test between the above-mentioned embodiment and the conventional example.

First, the NZ sound and 2N are plotted on the horizontal axis of the air volume.
As shown in FIG. 5 (A) in which the sound pressure level of the Z sound is plotted on the vertical axis, if the air flow rate is the same, the characteristic that the Δ marks are connected by the broken line
Compared with the sound pressure level of the 2NZ sound of the conventional example shown by (A), the sound pressure level of the 2NZ sound of the cross flow fan of the present invention shown by the characteristic (II) in which the circles are connected by the broken line is significantly reduced (maximum). 8 dB decrease).

Similarly, as shown in FIG. 5 (A), compared with the sound pressure level of the NZ sound of the conventional example shown by the characteristic (U) in which the Δ mark is connected by the solid line, the characteristic in which the ◯ mark is connected by the solid line is shown. The sound pressure level of the NZ sound of the cross flow fan of the present invention shown by (E) is reduced.

Further, as shown in FIG. 5B, compared with the sound pressure level of the blast sound of the conventional example indicated by the characteristic (o) indicated by the triangle mark and the solid line, the characteristic (or) indicated by the circle mark and the solid line. The sound pressure level of the blowing noise of the cross-flow fan of the present invention indicated by is decreased by about 2 dB.

Further, as can be seen by comparing the frequency characteristic of the sound pressure level of the embodiment shown in FIG. 6 with the frequency characteristic of the conventional example shown in FIG. 7, the protrusion of the sound pressure level at the frequency 2NZ is almost completely eliminated. I was able to resolve it.

As described above, according to the above-described embodiment, the peak sound can be reduced without deteriorating the air blowing characteristics.
A significant noise reduction can be realized.

[0020]

As is apparent from the above, in the cross flow fan of the present invention, arc blades of an impeller are arranged in the circumferential direction at random pitch angles, and a plurality of the impellers are arranged in the rotation axis direction. And, the plurality of impellers are circumferentially arranged at 1 ° to 4 °.
Since the positions are shifted one by one, compared to the conventional example in which the pitch angle is the same and the one in which the impeller is displaced by more than 4 ° in the circumferential direction, the peak sound can be reduced and a significant noise reduction is realized. it can.

[Brief description of drawings]

FIG. 1 is a diagram showing an arrangement of arc blades of an embodiment of a cross flow fan of the present invention.

FIG. 2 is a perspective view briefly showing the structure of the above embodiment.

FIG. 3 is a diagram showing an arrangement of arc blades of a conventional cross-flow fan.

FIG. 4 is a perspective view simply showing the structure of the conventional example.

FIG. 5 is a diagram showing noise characteristics of the example and the conventional example.

FIG. 6 is a diagram showing a frequency spectrum of a sound pressure level in the above embodiment.

FIG. 7 is a diagram showing a frequency spectrum of a sound pressure level of the conventional example.

FIG. 8 is a diagram showing a frequency spectrum of a sound pressure level when the skew angle of the impeller is set to 2 °, 34 °, and 36 °.

[Explanation of symbols]

 1 ... Arc blade, 2 ... Impeller.

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[Procedure amendment]

[Submission date] October 29, 1992

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 2

[Correction method] Change

[Correction content]

[Fig. 2]

Claims (1)

[Claims] 1. A cross-flow fan including an impeller having a plurality of forwardly curved arc blades, wherein arc blades of the impeller are circumferentially arranged at a random pitch angle, and the impeller is arranged in a rotational axis direction. Array multiple
A cross-flow fan, wherein the plurality of impellers are displaced by 1 ° to 4 ° in the circumferential direction.