JPH0960600A - Mixed flow fan provided with muffler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To drastically decrease noise by adjusting characteristics of frequency in absorbing sound. SOLUTION: A fan outer cylinder 7 is provided outside an outer peripheral sound absorbing material 9 through a protrusion as a spacer, and an air layer is formed as a sound absorbing part between them. A core muffling part 8 is provided on the center part of the fan outer cylinder 7, and the core muffling part 8 is formed of a plurality of incombustible non-woven fabrics and surrounds an incombustible muffling material. A steel plate-made pipe is provided on the suction side on the inner circumference of the outer peripheral muffling part 9, so as to be taken as a muffling structure.

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.

[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 vane, and a motor, and there is no known example in which a silencer is attached upstream of the mixed flow fan.

[0003]

In the conventional mixed flow fan, since the sound absorbing material is provided on the upstream side and the silencer (split silencer) for dividing the flow path is provided, the ventilation resistance is large and the performance is deteriorated. did. Further, there is a drawback that flow separation and vortex are generated by the split type sound absorbing material provided on the upstream side, and 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 object, the present invention provides a mixed flow fan with a low silencer and a high silencing effect. Therefore, in the present invention,
The fan casing of the outer cylinder is attached via an air layer between the fan outer cylinder and the outer peripheral sound absorbing material.The concrete structure of the outer peripheral sound absorbing material is such that the density of the sound absorbing material such as glass wool is continuous in the thickness direction. It is made of a sound absorbing structure that changes to. In the sound absorbing structure, for example, a surface having a low density is arranged on the inner side surface of the outer peripheral sound absorbing material, and a surface having a high density is arranged on the outer surface portion. Further, an outer cylinder casing is attached to the outer surface of the outer peripheral sound absorbing material via a protrusion as a spacer, and an air layer as a sound absorbing portion is defined between them. Further, in the present invention, a core muffling section is attached to the center of the fan outer cylinder, and the concrete structure of the core muffling section is a structure in which a sound absorbing material such as glass wool is wrapped with a core skin section, and the core skin section is Is a material of a plurality of non-combustible non-woven fabrics (felt such as glass fiber). As for the outer peripheral sound absorbing part, the outer peripheral sound absorbing part has a structure of an outer peripheral sound absorbing part in which a non-combustible fiber is lined on the inner peripheral part.

The core skin portion and the outer peripheral sound absorbing portion are formed by impregnating a non-combustible non-woven fabric or a non-combustible sound absorbing material with an adhesive and heating and pressing to form the non-combustible sound absorbing material (glass wool, etc.) together with the air flow. The form does not scatter.

[0006]

In the present invention, by utilizing the property that the flow of the air flowing through the mixed flow fan flows on the outer peripheral side of the muffler and does not flow much on the inner peripheral side, the fan outer cylinder and the outer periphery are improved in order to improve the muffling effect. An air layer is provided between the sound absorbing materials. As the outer peripheral sound absorbing material, a sound absorbing material such as glass wool is formed by a sound absorbing structure whose density continuously changes in the thickness direction. A casing of an outer cylinder is attached to the outside of the outer peripheral sound absorbing material via a protrusion as a spacer, and an air layer as a sound absorbing portion is provided between them, so that the sound transmitted from the fan outer cylinder is reduced. In addition, the effect of the outer peripheral sound absorbing material is added, whereby the frequency characteristic of sound absorption can be adjusted as desired, and noise in a wide frequency range is reduced. The structure of the outer peripheral sound absorbing part is to form an outer peripheral sound absorbing part in which a non-combustible fiber is lined on the inner peripheral side of the outer peripheral sound absorbing material.

An egg-shaped core silencer is provided near the center of the fan outer cylinder. The egg-shaped core muffling section has a small sound absorption area but a small ventilation resistance, and the generation of vortices in the vicinity of the downstream impeller reduces the noise of the mixed flow fan. Since the sound is reduced, the noise is reduced in a wide frequency range even on the suction port side of the fan with a silencer. The specific structure of the core sound deadening part is to have a structure in which the core sound deadening part is wrapped with a sound absorbing material such as glass wool in the core skin, and the core skin is made of multiple non-combustible non-woven fabrics (felt such as glass fiber). Is. Regarding the fixing structure of the core sound deadening part, the support plate attached to the core sound deadening part is fitted and fixed to the outer peripheral sound absorbing part.

In order to further enhance the sound deadening effect, a steel plate pipe is attached inside the suction side of the outer peripheral sound absorbing portion, and the sound of the mixed flow fan is mixed in the annular space surrounded by the fan outer cylinder and the steel plate pipe. The noise from the fan is randomly reflected after the incident, and the reflected sound when returning to the ventilation resistance and the sound newly incident from the mixed flow fan interfere with each other to reduce the noise in the low frequency range of 500 Hz or less.

According to the above-mentioned invention, a silent fan having a low noise can be provided by attaching a muffler having a small ventilation resistance and a high muffling effect.

[0010]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a vertical sectional view of a mixed flow fan with a silencer. 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. The mixed flow fan is a fan. Fixed plate 15
It is fixed to the fan outer cylinder 7. Mixed flow impeller 2
Is driven by the motor 6, the suction flow 13 flows into the impeller 2 from the suction port 10 through the fan outer cylinder 7, passes through the impeller, passes through the return guide vane 5, and the discharge flow 13d is discharged. Discharge from the outlet 11.

As shown in FIG. 1, on the inner peripheral portion of the fan outer cylinder 7,
The outer peripheral sound absorbing material 9 is provided, and the fan outer cylinder 7 is attached to the outer side surface 9b of the outer peripheral sound absorbing material 9 via the protrusion 16 as a spacer, and the air layer 17 as a sound absorbing portion is formed therebetween. A sound deadening flow path 12 is formed by the outer peripheral sound absorbing material 9, an egg-shaped core sound deadening portion 8 is provided in the fan outer cylinder 7, and a steel plate pipe 14 having a thickness of 1 mm is provided on the inner circumference of the outer peripheral sound absorbing material 9 on the suction port side. Is provided. The length L ₂ of the steel pipe 14 is 0.2 for L ₂ / L ₁ .
5 is set.

FIG. 2 is a cross-sectional view of the mixed flow fan with silencer according to the present invention. Core skin and outer cylinder sound absorbing material 9
The inner peripheral portion is formed of non-combustible non-woven fabric (felt such as glass fiber), and the outer cylinder sound absorbing material 9 is formed of a sound absorbing body whose density continuously changes in the thickness direction. In the sound absorbing material structure, a surface having a low density is arranged on the inner side surface 9a of the outer cylinder sound absorbing material 9 and a surface having a high density is arranged on the outer surface 9b, respectively.
As a fan casing, through the air layer 17 on the outside,
A double fan casing structure is used in which the fan outer cylinder 7 is a second fan casing.

[0014]

According to the present invention, the outer peripheral sound absorbing member is formed of a sound absorbing structure in which the density is changed in the thickness direction, and the fan outer cylinder is attached to the outer side of the outer peripheral sound absorbing member via the air layer. As a result, noise can be significantly reduced.

Further, a core sound deadening part is attached to the center of the fan outer cylinder, and the core sound deadening part has a structure in which a nonflammable sound absorbing material (such as glass wool) is wrapped with a plurality of nonflammable nonwoven fabrics. Then, the support plate connected to the core muffling section is fitted into the fan outer cylinder to fix the core muffling section. On the other hand, the outer peripheral sound absorbing part has a structure in which a non-combustible fiber (glass cloth, etc.) is lined on the inner periphery of the outer peripheral sound absorbing material, and a steel pipe is attached to the suction port side on the inner periphery of the outer peripheral sound absorbing part. Form a silencer structure.

With each of the above-mentioned sound deadening mechanisms, the frequency characteristics of sound absorption can be adjusted as desired, and a significant reduction in noise can be achieved. In addition, since it is reduced in a wide range from low frequency range to high frequency range, it becomes a quiet and soft timbre.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a mixed flow fan with a silencer according to the present invention.

FIG. 2 is a cross-sectional view of a mixed flow fan with a silencer according to the present invention.

[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 part, 9 ... Perimeter sound absorbing material, 9a ... Inner side surface of outer sound absorbing material, 9b ... Outer surface of outer sound absorbing material, 10 ... Suction port, 11 ... Discharge port, Reference numeral 12 is a muffler flow passage, 14 is a steel plate pipe, and 15 is a fan fixing plate.

Claims (1)

[Claims] 1. A mixed flow fan with a silencer, wherein a mixed flow fan comprising a mixed flow impeller and a return vane, and a fan outer cylinder having an outer peripheral sound absorbing material attached upstream of the mixed flow fan are connected.
A mixed flow fan with a silencer, wherein the fan outer cylinder is provided as an outer fan casing on the outer side of the outer peripheral sound absorbing material via an air layer.