CN107882777A - A kind of suppression noise structure for blower fan - Google Patents

Abstract

The invention discloses a noise suppression structure for a fan, belonging to the technical field of fan equipment. In the prior art fan noise reduction structure, the bottom of the perforated plate shares the same cavity, resulting in a narrow resonance frequency band, which can only absorb single-frequency noise, narrow noise reduction band, and poor noise reduction effect, resulting in high noise when the fan is working and poor user experience. The lower end surface of the bracket of the present invention is provided with inner and outer two-layer ring walls, a first sound-absorbing chamber is formed between the two layers of ring walls, and a small groove is opened on the lower end surface of the inner ring wall, and the ring wall of the bracket interferes with the first ring wall on the variable-diameter housing. On the flat part, the noise enters the first muffler chamber from the small groove, and the absorbed noise collides repeatedly in the first muffler chamber to reduce the noise. The present invention is provided with a first sound-absorbing cavity for absorbing noise, has simple manufacturing process and low manufacturing cost, can absorb noise of various frequencies at the same time, has wide frequency band of sound-absorbing frequency, and has good noise-reducing effect.

Description

A Noise Suppression Structure for Fans

technical field

The invention relates to a noise suppression structure for a fan, belonging to the technical field of fan equipment.

Background technique

The noise suppression structure used for fans in the prior art usually adopts the Helmholtz resonance muffler, which has a simple structure. By setting different structures of noise reduction and noise reduction structures, the middle and high frequency noise can be suppressed. At present, its disadvantage is that one structure can only Absorbs single-frequency noise and has a narrow frequency-cancellation band. In the actual use process, the fan changes with the external conditions, and the noise frequency also changes. During use, adding porous materials to the inner wall of the resonance cavity or designing a porous structure can enhance the sound-absorbing effect, which not only increases the complexity of the product manufacturing process, but also increases the cost. The sound absorption effect of porous structure may not be ideal for some materials, and each resonant structure has the same natural frequency, which is determined by the small hole diameter d, pore cross-sectional area s and cavity volume V of the resonant structure. Because the same cavity is shared under the perforated plate, the resonance frequency band is narrow, and only a single frequency noise can be absorbed. The noise reduction band is narrow, and the noise reduction effect is poor, resulting in high noise when the fan is working, and poor user experience.

Contents of the invention

Aiming at the defects of the prior art, the purpose of the present invention is to provide a noise suppression structure for fans with simple manufacturing process and low manufacturing cost, which can absorb noise of various frequencies, has a wide frequency band of noise reduction, and has a good noise reduction effect.

To achieve the above object, the technical solution of the present invention is:

A noise suppression structure for a fan, comprising a bracket with a through slot, an annular air deflector is connected under the bracket, the outer end surface of the annular air deflector is a variable-diameter casing, and a first flat surface is arranged on the upper end surface. The lower end of the bracket is provided with inner and outer two-layer ring walls, a first muffler cavity is formed between the two layers of ring walls, and a small groove is opened on the lower end of the inner ring wall. On the first flat part, the noise enters the first muffler chamber from the small groove, and the absorbed noise collides repeatedly in the first muffler chamber to reduce the noise. The present invention can be installed at the air outlet and/or air inlet of the fan, and has a wide range of applications. By setting the first sound-absorbing cavity, it is used to absorb noise. The manufacturing process is simple and the manufacturing cost is low. At the same time, it can absorb noise of various frequencies, and the sound-cancelling bandwidth is wide. Noise reduction is good.

As an optimal technical measure, several partitions are arranged between the ring walls on both sides to divide the first sound-absorbing chamber into several small sound-absorbing chambers, and gaps are opened in some of the partitions. The first sound-absorbing chamber is divided into multiple small sound-absorbing chambers, forming a resonant coupling structure between them, which expands the sound absorption spectrum and enhances the noise reduction effect.

As an optimal technical measure, the bracket is provided with a first wind collection ring surface extending obliquely upwards, and the annular air guide plate is provided with a second wind collection ring surface extending upwards, and the second wind collection ring surface is connected with the first wind collection Keep a certain distance from the wind ring surface to form an air collecting port. Before the noise enters the first muffler cavity, it first enters the narrow and long annular cavity formed by the first wind collecting ring surface and the second wind collecting ring surface, and the noise keeps reciprocating to form an air column to reduce the noise energy. When the natural frequency of the resonant sound-absorbing structure is the same, the resonance phenomenon will occur, which means that the amplitude reaches the maximum, and the speed of the reciprocating motion of the air column in the aperture is the maximum. Similar to a spring model, the friction loss is the largest, and the absorbed sound energy also reaches the maximum. , so that the noise energy gradually decreases and the sound pressure decreases.

As an optimal technical measure, a sound cavity cover is installed under the annular air deflector, and a second horizontal part is arranged at the end of the upper end of the sound cavity cover. On the second horizontal part, the two are screwed together, which can be connected by coarse-threaded screws to ensure the sealing reliability of the contact area between the sound chamber cover and the annular air guide plate, and at the same time, it is easy to disassemble.

As a preferred technical measure, a through hole is opened in the middle of the sound cavity cover, and extends upward to form a third wind collecting ring surface, and the third wind collecting ring surface is kept at a certain distance from the second wind collecting ring surface to form a second muffler chamber . The first sound-absorbing chamber is divided into multiple sound-cavities, forming a resonant coupling structure between them, and then forms a multi-cavity resonant coupling structure with the second sound-absorbing chamber structure, which expands the sound absorption spectrum and increases the noise reduction effect.

As a preferred technical measure, the port distance between the first wind collecting ring surface and the second wind collecting ring surface is d1, and the port distance between the second wind collecting ring surface and the third wind collecting ring surface is d2. The principle of the Helmholtz resonance muffler is excited by the external sound field and consumes its energy to become a sound absorbing body. In order to achieve the best sound absorption effect, the value range of d1 and d2 is between 0.5mm-3mm.

As an optimal technical measure, the bracket, the annular air deflector, and the sound cavity cover are of concentric shaft structure, arranged in order from top to bottom, which is convenient for assembly and maintenance.

As a preferred technical measure, the middle position of the annular air deflector is provided with a collecting port that penetrates up and down, the diameter of the collecting port is L2, the diameter of the bracket through-slot is L1, and the diameter of the through-hole of the sound cavity cover is L3 , the L1, L2, and L3 are equal, which can reduce the noise caused by the unevenness of the pipeline and the impact on the wall surface and the influence of the air intake resistance.

As an optimal technical measure, the lower end of the sound chamber cover is provided with a slot for installing a mask, so as to ensure a compact overall structure, facilitate manufacturing, and save costs.

As an optimal technical measure, the noise suppression structure is provided with a frame for covering the fan. The frame is a square shell, which effectively protects the internal components from being damaged by other external things, and at the same time plays a certain noise reduction effect.

Compared with the prior art, the present invention has the following beneficial effects:

The present invention is provided with a first sound-absorbing cavity for absorbing noise, has a simple manufacturing process and low manufacturing cost, and can absorb noise of various frequencies at the same time, has a wide band of sound-absorbing frequencies, and has a good noise-reducing effect.

Further, the first sound-absorbing chamber is divided into multiple sound-cavities, forming a resonant coupling structure among them, and then forms a multi-cavity resonant coupling structure with the second sound-absorbing chamber structure, which expands the sound absorption spectrum and increases the noise reduction effect.

The invention can be directly used for fan noise reduction of air heaters, ventilation fans or fresh air fans, the structure is easy to manufacture, and the scheme is practical.

Description of drawings

Fig. 1 is the structural representation of fan assembly of the present invention;

Fig. 2 is a cross-sectional view of the structure of the first sound-absorbing cavity of the present invention;

Fig. 3 is a cross-sectional view of the structure of the second sound-absorbing cavity of the present invention;

Fig. 4 is a schematic diagram of the stent structure of the present invention;

Fig. 5 is a sectional view of the bracket, the annular air deflector and the sound chamber cover of the present invention.

Explanation of reference signs:

1-bracket, 2-annular wind deflector, 3-sound chamber cover, 4-frame, 5-fan, 6-wind shell, 7-ring support, 8-mask, 11-inner ring wall, 12-outer ring Wall, 13-small groove, 14-baffle, 15-notch, 16-first wind collecting ring, 17-through groove, 21-first flat part, 22-second wind collecting ring, 23-collection Mouth, 31-the third wind collection ring surface, 32-the second flat part, 33-through hole, 34-drawing slot.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention.

On the contrary, the invention covers any alternatives, modifications, equivalent methods and schemes within the spirit and scope of the invention as defined by the claims. Further, in order to make the public have a better understanding of the present invention, some specific details are described in detail in the detailed description of the present invention below. The present invention can be fully understood by those skilled in the art without the description of these detailed parts.

It should be noted that when an element is referred to as being “fixed” to another element, it can be directly on the other element or there can also be an intervening element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or intervening elements may also be present. In contrast, when an element is referred to as being "directly on" another element, there are no intervening elements present. The terms "upper", "lower" and similar expressions are used herein for the purpose of description only.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field of the invention. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

As shown in FIGS. 1-5 , a noise suppression structure for a fan includes a bracket 1 with a through slot 17 , an air shell 6 , a ring support 7 , a sound chamber cover 3 , and a face shield 8 . The noise suppressing structure is provided with a frame 4 for covering the fan 5 , the frame 4 is a square shell, the bracket 1 is installed under the fan 5 , and a ring-shaped wind deflector 2 is connected to the bottom of the bracket 1 . The lower end of the sound chamber cover 3 is provided with a slot 34 for installing the mask 8, so as to ensure a simple overall structure and save costs. The support 1 , the annular air deflector 2 and the sound chamber cover 3 are concentric shaft structures arranged in sequence from top to bottom. The annular support 7 includes an annular PTC and an outer bracket.

The outer end surface of the annular wind deflector 2 is a variable-diameter housing, and the first flat part 21 is arranged on the upper end surface, and the inner and outer two-layer ring walls are arranged on the lower end surface of the support 1, which includes an inner ring wall 11 and an outer ring wall 12. , the first muffler cavity is formed between the two layers of ring walls, and the lower end surface of the inner ring wall 11 is provided with a small groove 13, and the ring wall of the bracket 1 is in contact with the first flat part 21 on the variable diameter housing, and the two sides Several partitions 14 are arranged between the ring walls to divide the first sound-absorbing chamber into several small sound-absorbing chambers, some of which have gaps 15 in the partitions 14, and the partitions 14 also play a role in strengthening the strength of the bracket 1. Noise enters the first sound-absorbing chamber from the small groove 13, and the absorbed noise collides repeatedly in the first sound-absorbing chamber to reduce noise.

The bracket 1 is provided with a first wind collecting ring surface 16 extending obliquely upward, and the annular wind deflector 2 is provided with a second wind collecting ring surface 22 extending upwards, and the second wind collecting ring surface 22 is connected with the first collecting ring surface. The wind ring surface 16 keeps a certain distance to form an air collecting port. A sound chamber cover 3 is installed below the annular wind deflector 2, and a second horizontal part is arranged at the end of the upper end of the sound chamber cover 3, and the sound chamber cover 3 is set on the ring-shaped wind deflector 2, and its lower end surface is in contact with the on the second level. A through hole 33 is opened in the middle of the sound chamber cover 3, and extends upward to form a third wind collecting ring surface 31, and the third wind collecting ring surface 31 is kept at a certain distance from the second wind collecting ring surface 22 to form a second muffler chamber . The middle position of the annular wind deflector 2 is provided with a collecting port 23 that penetrates up and down. The diameter of the collecting port 23 is L2, the diameter of the through groove 17 of the bracket 1 is L1, and the diameter of the through hole 33 of the sound cavity cover 3 is L2. L3, the L1, L2, and L3 are equal, which can reduce the noise caused by the unevenness of the pipeline and the impact on the wall surface and the influence of the air intake resistance.

The sound-absorbing structure of the present invention adopts the principle of the Helmholtz resonance muffler, which is excited by the external sound field and consumes its energy to become a sound-absorbing body. In order to achieve the best sound absorption effect, its size design also has strict requirements. According to the simple expression of the resonance frequency of the Helmholtz resonance muffler:

Where: f0 is the resonance frequency of the Helmholtz resonance muffler, с is the speed of sound, s is the cross-sectional area of the neck or opening, d is the diameter of the neck or opening, l is the length of the neck, and V is the volume of the container. Under the action of sound waves with a certain intensity, at this resonance frequency, the vibration speed of the air in the neck is the largest. If the size of d is small enough, the airflow in the neck will generate acoustic resistance due to the viscous resistance of the air, which will help to better suppress the noise from the air inlet. The port distance between the first wind-collecting ring surface 16 and the second wind-collecting ring surface 22 is d1, and the port distance between the second wind-collecting ring surface 22 and the third wind-collecting ring surface 31 is d2, calculated by the above formula It can be seen that the value range of d1 and d2 is between 0.5mm-3mm.

When the fan 5 is running, the noise generated by the fan 5 is mainly concentrated in the cavity 17 of the bracket 1. By setting the annular air guide plate 2 and the sound chamber cover 3, the noise in the channel 17 can be respectively absorbed by the second ring of the annular air guide plate 2. The wind-collecting ring surface 22 and the third wind-collecting ring surface 31 of the sound chamber cover 3 are guided and smoothly absorbed by the first sound-absorbing chamber and the second sound-absorbing chamber. The energy of this process is reduced. And before the noise enters the first muffler cavity, it first enters the narrow and long annular cavity formed by the first wind collecting ring surface 16 and the second wind collecting ring surface 22, and the noise keeps reciprocating to form an air column, reducing the noise energy, When the frequency of the sound wave is the same as the natural frequency of the resonant sound-absorbing structure, the resonance phenomenon will occur, which means that the amplitude reaches the maximum, and the reciprocating speed of the air column in the aperture is the maximum, similar to a spring model, the friction loss is the largest, and the absorbed sound energy is also When reaching the maximum value, the noise energy gradually decreases and the sound pressure decreases. At the same time, the first sound-absorbing chamber is divided into multiple sound-absorbing chambers, forming a resonant coupling structure among them, and then forms a multi-cavity resonant coupling structure with the second sound-absorbing chamber structure, which expands the sound absorption spectrum.

After testing, in the frequency band of 300Hz~6000Hz, the multi-cavity resonance coupling structure formed by the second noise reduction chamber and the first noise reduction chamber (multi-cavity body) expands the noise reduction spectrum bandwidth and improves the noise suppression effect of the resonance coupling structure , the present invention reduces noise by at least 1.6dB or more.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention should be included in the protection of the present invention. within range.

Claims (10)

1. A noise suppression structure for a fan, comprising a bracket (1) with a through slot (17), characterized in that an annular air deflector (2) is connected under the bracket (1), and the annular air guide The outer end surface of the air plate (2) is a variable-diameter shell, and the upper end surface is provided with a first flat part (21), and the lower end surface of the bracket (1) is provided with two inner and outer ring walls, and a first In the muffler chamber, a small groove (13) is opened on the lower end surface of the inner ring wall (11), and the ring wall of the bracket (1) is in contact with the first flat part (21) on the variable diameter housing, and the noise comes from the small groove (13) ) into the first muffler cavity, the absorbed noise collides repeatedly in the first muffler cavity to reduce the noise. 2. A noise suppression structure for fans according to claim 1, characterized in that several partitions (14) are arranged between the ring walls on both sides to divide the first sound-absorbing chamber into several small sound-absorbing chambers , where part of the dividing plate (14) offers gaps (15). 3. A noise suppression structure for fans according to claim 1, characterized in that, the bracket (1) is provided with a first wind collection ring surface (16) extending obliquely upward, and the ring guide wind The plate (2) is provided with a second wind-collecting ring surface (22) extending upwards, and the second wind-collecting ring surface (22) is kept at a certain distance from the first wind-collecting ring surface (16) to form an air-collecting opening. 4. A noise suppression structure for fans according to claim 3, characterized in that, a sound cavity cover (3) is installed under the annular wind deflector (2), and the sound cavity cover (3) A second horizontal part is provided at the end of the upper end surface, and the ring-shaped air deflector (2) is covered with a sound cavity cover (3), and its lower end surface is in contact with the second horizontal part. 5. A noise suppression structure for fans according to claim 4, characterized in that a through hole (33) is opened in the middle of the sound chamber cover (3) and extends upward to form a third wind collection ring surface ( 31), the third wind-collecting ring surface (31) is kept at a certain distance from the second wind-collecting ring surface (22) to form a second muffler cavity. 6. A noise suppression structure for fans according to claim 5, characterized in that, the port distance between the first wind collecting ring surface (16) and the second wind collecting ring surface (22) is d1, The port distance between the second wind-collecting ring surface (22) and the third wind-collecting ring surface (31) is d2, and the value range of d1 and d2 is between 0.5mm-3mm. 7. A noise suppression structure for fans according to claim 4, characterized in that, the bracket (1), the annular wind deflector (2), and the sound chamber cover (3) are concentric shaft structures , in order from top to bottom. 8. A noise suppression structure for fans according to claim 7, characterized in that, the middle position of the annular air deflector (2) is provided with a collecting port (23) that penetrates up and down, and the collecting port The diameter of (23) is L2, the diameter of the through groove (17) of the bracket (1) is L1, the diameter of the through hole (33) of the sound cavity cover (3) is L3, and the three of L1, L2 and L3 are equal . 9. A noise suppression structure for fans according to any one of claims 1-8, characterized in that, the lower end of the sound chamber cover (3) is provided with a slot (34) for installing the mask (8) . 10. A noise suppression structure for a fan according to claim 9, characterized in that the noise suppression structure is provided with a frame (4) for covering the fan (5), and the frame (4) is a square shell body.