JP2770677B2 - Cross flow fan - Google Patents

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 for an air conditioner or the like, and more particularly to a cross flow fan capable of reducing a 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, a plurality of impellers 30 are arranged in a staggered manner in the rotation axis direction so that the circumferential phases of the arc-shaped blades 31 of every other impeller 30 in the rotation axis direction are the same.

[0003]

However, in the above-mentioned conventional cross flow fan, an NZ sound which is a sound having a frequency of a product NZ of a fan rotation speed N per second and the number Z of arc blades,
There is a problem that the 2NZ sound, which is a sound having a frequency of 2NZ twice as large as the product NZ, is significantly louder than sounds of other frequencies, and generates noise that is unpleasant in audibility. 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 for increasing the A-scale sound as the overall sound.

Accordingly, an object of the present invention is to provide a cross flow fan that can reduce the noise level.

[0005]

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

[0006]

According to the above arrangement, as shown in FIG. 5A in which the air volume is plotted on the horizontal axis and the sound pressure levels of the NZ sound and the 2NZ sound are plotted on the vertical axis, if the air volume is the same, a triangle is indicated. Compared with the sound pressure level of the conventional 2NZ sound indicated by the characteristic (a) connected by the broken line, the sound pressure level of the 2NZ sound of the cross flow fan of the present invention indicated by the characteristic (i) indicated by the broken line is significantly larger than that of the conventional example. Decreased to.

Also, as shown in FIG. 5A, the characteristic in which a triangle is connected by a solid line is different from the sound pressure level of a conventional NZ sound indicated by a characteristic in which a triangle is connected by a solid line. (E) shows that the sound pressure level of the NZ sound of the cross flow fan of the present invention is reduced.

Further, as shown in FIG. 5B, the characteristic (?) Indicated by the solid triangle and the solid line is smaller than the sound pressure level of the blown sound of the conventional example indicated by the characteristic (O) indicated by the solid triangle and the solid line. The sound pressure level of the blowing noise of the cross flow fan according to the present invention, which is indicated by, is reduced.

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

On the other hand, a plurality of impellers are set at 2 ° in the circumferential direction.
According to the cross flow fan having a skew angle of 2 ° according to the present invention, the position of which is shifted by one at a time, as shown in FIG.
The peak sound shown in (C) could be eliminated.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the illustrated embodiments.

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

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 results of a comparative noise test between the above embodiment and the conventional example.

First, the NZ sound and the 2N
As shown in FIG. 5 (A) in which the sound pressure level of the Z sound is plotted on the vertical axis, when the air volume is the same, the characteristic is indicated by connecting the dashes with broken lines.
Compared with the sound pressure level of the conventional 2NZ sound shown by (a), the sound pressure level of the 2NZ sound of the cross flow fan of the present invention shown by the characteristic (i) in which the mark is connected by a broken line is greatly reduced (maximum). 8 dB).

Also, as shown in FIG. 5A, compared with the sound pressure level of the NZ sound of the conventional example indicated by the characteristic (△) connected by a solid line, the characteristic connected by a solid line (E) shows that the sound pressure level of the NZ sound of the cross flow fan of the present invention is reduced.

As shown in FIG. 5 (B), the characteristic (?) Indicated by the solid triangle and the solid line is smaller than the sound pressure level of the conventional blown sound indicated by the characteristic (△) indicated by the solid line and the solid line. Indicates that the sound pressure level of the blowing noise of the cross flow fan of the present invention is reduced by about 2 dB.

Further, as can be seen by comparing the frequency characteristics of the sound pressure level of the above embodiment shown in FIG. 6 with the frequency characteristics 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 eliminate it.

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

[0020]

As is apparent from the above description, the cross flow fan of the present invention has circular arc blades of an impeller arranged at random pitch angles in the circumferential direction, and a plurality of the impellers arranged in the rotation axis direction. And the plurality of impellers are arranged at a circumferential angle of 1 ° to 4 °.
The peak noise can be reduced compared to the conventional example where the pitch angle is equal, and the impeller is shifted more than 4 ° in the circumferential direction, resulting in significant noise reduction. it can.

[Brief description of the drawings]

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

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

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

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

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

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

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

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

[Description of Signs] 1 ... arc blade, 2 ... impeller.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F04D 17/04 F04D 29/30 101 F04D 29/66

Claims (1)

(57) [Claims] 1. A cross flow fan comprising an impeller having a plurality of forwardly curved arc blades, wherein the arc blades of the impeller are arranged in a circumferential direction at a random pitch angle, and the impeller is rotated in a rotation axis direction. Are arranged in multiple,
A cross flow fan wherein the plurality of impellers are displaced by 1 ° to 4 ° in the circumferential direction.