JPH09158899A - Mixed flow fan with noise eliminator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To diminish ventilation resistance so as to improve a noise eliminating effect in a mixed flow fan with a noise eliminator formed by arranging on the upstream side of a mixed flow fan, a noise eliminating part consisting of a peripheral sound absorbing material and a silencer core, by sandwiching a supporting plate connected to the silencer core between a peripheral sound absorbing part and the divided part of an outer cylinder so that a core is fixed. SOLUTION: In a mixed flow fan with a noise eliminator, a peripheral sound absorbing material 9 is arranged on the inner circumferential side of a fan outer cylinder 7 so as to form a sound eliminating channel 12, and an eggy core sound eliminating part 8 is formed in the fan outer cylinder 7. When this sound eliminating part 8 is fixed to the outer cylinder 7, the sound eliminating part 8 is sandwiched between core mounting tools 18a, 18b and attached through a flange fastener. When the mounting tools 18a, 18b and the outer cylinder 7 are fixed, the mounting tool 18a is sandwiched between the flange parts of the fan outer cylinder 7 divided into two and fixed through an outer cylinder fastener 19. The core sound eliminating part 8 is thusly arranged in a place where a sound eliminating effect can be extremely obtained in the fan outer cylinder 7 so that ventilation resistance can be diminished while a sound absorbing area is enlarged, and a noise in a high frequency area can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a small mixed flow fan installed in a ceiling or a tunnel of a building or the like and used for an air conditioner booster or ventilation, and more particularly to a silencer for noise reduction. Regarding the structure.

[0002]

2. Description of the Related Art A conventional mixed flow fan is disclosed in Japanese Patent Laid-Open No. 61-261697.
As described in the publication, there is only a mixed flow fan composed of an impeller, a return guide vane and a motor, and there is no known example in which a silencer is attached upstream of the mixed flow fan as in the present invention. I couldn't do it.

[0003]

In the conventional mixed flow fan, since a muffler (split muffler) for dividing the flow path by providing a sound absorbing material on the upstream side is provided, the ventilation resistance is largely reduced. . In addition, the split type sound absorbing material provided on the upstream side causes flow separation and vortex, and there is a drawback that noise is increased due to the turbulence. Therefore, there has been a demand for a silent mixed flow fan provided with a silencer having a small ventilation resistance and a high silencing effect.

[0004]

In order to achieve the above-mentioned object, the present invention provides a mixed flow fan with a silencer having a small ventilation resistance and a high silencing effect. Therefore, in the present invention, a silencer core silencer is provided in the center of the fan outer cylinder, and the specific structure of the silencer core silencer is such that the silencer core silencer is a sound absorbing material such as glass wool wrapped in a silencer core skin. That is, the silencer core skin is made of a non-combustible non-woven fabric (felt such as glass fiber). Regarding the structure for fixing the silencer core muffling section, the support plate connected to the silencer core muffling section is sandwiched between the outer peripheral sound absorbing section and the divided section of the outer cylinder to fix the silencer core. Further, regarding the outer peripheral sound absorbing material, the bellows shape is provided on the inner periphery of the outer peripheral sound absorbing material on the side of the mixed flow fan suction. Also,
The inner peripheral surface of the outer peripheral sound absorbing material is impregnated with an adhesive so that the non-combustible sound absorbing material (such as glass wool) does not scatter with the airflow.

In the present invention, the nature of the flow of air in the muffler flowing outside the flow path and not flowing inside much makes use of the oval shape on the center line of the fan outer cylinder in order to improve the muffling effect. The silencer core silencer is installed. The egg-shaped silencer core muffler reduces the noise of the mixed flow fan because the ventilation resistance is small despite the large sound absorption area and the generation of vortices is small near the downstream impeller. Since direct noise of noise is reduced on the suction port side, noise is reduced in a wide range of frequencies on the suction port side of the fan with a silencer by adding the sound absorbing effect of the outer peripheral sound absorbing material.

The specific structure of the silencer core muffling section is as follows.
The silencer core sound deadening part has a structure in which a sound absorbing material such as glass wool is wrapped in a silencer core skin part, and the silencer core skin part is made of a non-combustible non-woven fabric (felt such as glass fiber). Regarding the structure for fixing the silencer core muffling section, the support plate connected to the silencer core muffling section is fixed by being sandwiched between the outer peripheral sound absorbing material and the divided portion of the outer cylinder.

Regarding the structure of the outer peripheral sound absorbing portion, the mixed flow fan suction port on the inner peripheral of the outer peripheral sound absorbing material has a bell mouth shape,
The structure is to minimize the vortex generated at the inlet of the mixed flow fan.

The outer peripheral sound absorbing material has an inner peripheral surface impregnated with an adhesive so that the non-combustible sound absorbing material (glass wool, etc.) does not scatter with the air flow.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a side sectional view of a mixed flow fan with a silencer. In FIG. 1, the mixed flow fan is composed of an impeller 2 having a plurality of blades 1, a return guide vane 5, an upper fan casing 3, a lower fan casing 4, a motor 6, and a fan outer cylinder 7. When the motor 6 is driven, the suction flow 1
3 flows from the suction port 10 through the fan outer cylinder 7 into the impeller 2, passes through the impeller, through the return guide vane 5, and the discharge flow 14 is discharged from the discharge port 11.

In the present invention, as shown in FIG. 1, an outer peripheral sound absorbing material 9 is provided on the inner peripheral side of the fan outer cylinder 7 to form a sound deadening flow path 12, and an oval core muffler is provided in the fan outer cylinder 7. 8 are provided.

FIG. 2 shows the installation position of the core muffling section 8 of the embodiment of the present invention. The installation direction of the egg-shaped core sound deadening part 8 is such that the gap between the surface layer surface of the core sound deadening part 8 and the outer peripheral sound absorbing material 9 is L ₄ <
L _5, L ₃ <is a direction in which the relationship of L _6. Further, the size of the diameter of the egg-shaped core silencing part 8 is such that D ₂ / D ₁ is 0.5 to 0 when the maximum diameter of the core silencing part 8 is D ₂ and the width of the silencing channel 12 is D _1. When it is set to 0.85, the gap L ₄ of the sound deadening flow path 12 is optimized, so that the ventilation resistance becomes small and the sound absorbing area also becomes large. Furthermore, the size of the distance L ₇ from the tip of the core muffling section 8 on the suction port 10 side to the end of the fan outer cylinder 7 and the distance L ₉ from the suction port 10 of the fan outer cylinder 7 to the core muffling section 8 are:
The length that reduces the noise emission from the suction port 10 is set to L ₉
/ L ₄ is 1.0 to 2.5, and the distance L ₈ from the tip of the core muffling section 8 to the tip of the blade 1 is a length at which the vortex of the flow generated in the core muffling section is attenuated, and L ₈ / L _The optimum value of ₄ is 1.5 to 4.0. In the embodiment of the present invention, the core muffling section 8 is set to L ₄ / D _{1
= 0.07~0.15, L 7 / L 4} = 0, L 9 / L 4 = 1.0
It is installed in such a position as to reduce noise.

FIG. 3 is an explanatory view of a method for manufacturing the core muffling section 8 of the embodiment of the present invention. In the present invention, the core sound absorbing portion is wrapped with the non-combustible nonwoven fabric 16 to form the core sound absorbing portion 8.

FIG. 4 shows an embodiment of manufacturing the core skin portion 16. A core skin 16a is produced by heat-processing non-combustible fiber, the flange 16b of the skin 16a is aligned, and the core sound deadening part 8a (glass wool) is heat-sealed so as not to scatter with the airflow.

FIG. 5 shows a state in which the core muffling section 8 of the present invention is fixed to the fan outer cylinder 7. The core sound absorbing material 8 a is packed inside the core skin portion 16 to form the core sound deadening portion 8. Further, the core silencer 8 is attached to the core attachments 18a and 1
It is sandwiched by 8b and attached via a flange stopper 16c.
For fixing the core attachments 18a and 18b to the outer cylinder 7,
A core portion mounting tool 18a is sandwiched between the flange portions of the fan outer cylinder 7 divided into two, and the core outer mounting tool 18 is fixed via an outer cylinder stopper 19.

Although the silent structure of the mixed flow fan has been described with reference to the embodiments of FIGS. 1 to 5, according to the present invention, by installing the egg-shaped core muffling section 8, it is possible to reduce the noise by about 20 dB in the high frequency range and further absorb the outer peripheral noise. Since the wide frequency range is made quiet by the material 9, the soft tone is produced with no outstanding sound.

[0017]

EFFECTS OF THE INVENTION According to the present invention, the egg-shaped core muffling section is grounded at the place where the maximum silencing effect can be achieved in the fan outer cylinder, so that the sound absorbing area is large and the ventilation resistance is small. The vortex of the flow in the muffling section is attenuated, the noise radiation amount is reduced, and the noise in the high frequency range can be reduced.

Further, according to the present invention, a core sound deadening portion is attached to the center of the fan outer cylinder, and the core sound deadening portion has a structure in which a nonflammable sound absorbing material (glass wool) is wrapped with a plurality of nonflammable nonwoven fabrics. The support plate connected to the core muffling section is sandwiched by the outer peripheral sound absorbing material to fix the core muffling section.

Further, the bellows shape of the mixed flow fan suction port on the inner circumference of the outer peripheral sound absorbing material can be reduced to reduce noise caused by vortices generated near the mixed flow fan suction port.

With each of the above-mentioned sound deadening mechanisms, approximately 2 in a wide frequency range.
Noise of 0 dB is reduced, resulting in a quiet and soft timbre.

[Brief description of the drawings]

FIG. 1 is a sectional view of a mixed flow fan according to the present invention.

FIG. 2 is a sectional view of an embodiment of the present invention.

FIG. 3 is a sectional view of a second embodiment of the present invention.

FIG. 4 is a cross-sectional view of the core muffling section of FIG.

5 is a cross-sectional view of FIG.

[Explanation of symbols]

1 ... Blade, 2 ... Impeller, 3 ... Upper fan casing, 4
… Lower fan casing, 5… Return guide vanes,
6 ... Motor, 7 ... Fan outer cylinder, 8 ... Core muffling section, 8a ...
Core part sound absorbing material, 9 ... Peripheral sound absorbing material, 9a ... Skin, 10 ... Suction port, 11 ... Discharge port, 12 ... Silence passage, 13 ... Suction flow,
13a, 13b, 13c ... Flow, 14 ... Discharge flow, 15 ...
Bell mouth department.

Claims (1)

[Claims] 1. A muffler having an integrated structure in which a mixed flow fan composed of a mixed flow impeller and a return guide vane and a muffling section composed of an outer peripheral sound absorbing material and a silencer core are arranged on the upstream side of the mixed flow fan. A mixed flow fan with a silencer, wherein a support plate connected to the silencer core is sandwiched between the outer peripheral sound absorbing portion and the divided portion of the outer cylinder to fix the silencer core.