A low-noise fan module

Abstract

The utility model discloses a low noise's fan module, including the head structure of long barrel, the head structure includes the air duct that is enclosed by the casing, the impeller of setting in the air duct and be used for driving the drive unit of impeller, the impeller is placed in the middle section position in the casing, the axial front end of impeller corresponds the air intake of air duct, the axial rear end of impeller corresponds the air outlet of air duct, be equipped with the air cutting bone of the clearance cooperation of fan blade with the impeller in the air outlet, the axial length of air cutting bone is equivalent to the interval between fan blade and air intake. The utility model has can guarantee the premise under the premise of not reducing the wind amount, realizes the relatively low noise's advantage of fan module.

Description

Technical Field

[0001] This utility model belongs to the field of fan technology, and in particular relates to a low-noise fan module. Background Technology

[0002] To concentrate airflow, existing fan module heads are typically long and cylindrical, with the impeller located in the middle of the inner side of the cylinder. However, this structural layout causes noise sources to form and overlap during the airflow intake and exhaust phases. Furthermore, periodic airflow disturbances are generated when each blade of the impeller rotates, producing blade-passing frequency noise, which makes it impossible to effectively manage the noise. Summary of the Invention

[0003] To address the shortcomings of existing technologies, a low-noise fan module is provided.

[0004] This utility model is achieved using the following technical solution:

[0005] A low-noise fan module includes a long cylindrical head structure. The head structure includes an air duct formed by a housing, an impeller disposed within the air duct, and a drive unit for driving the impeller. The impeller is located in the middle section of the housing. The axial front end of the impeller corresponds to the air inlet of the air duct, and the axial rear end of the impeller corresponds to the air outlet of the air duct. The air outlet is provided with a cutting rib that fits with the fan blades of the impeller. The axial length of the cutting rib is equal to the distance between the fan blades and the air inlet, so that the two ends of the impeller are at a certain distance from the air inlet and the air outlet.

[0006] The drive unit can be a wire used to drive the impeller to rotate or other existing technology structures that provide power to the impeller.

[0007] By making the axial length of the air cutter equal to the distance between the impeller and the air inlet, a resonant cavity is formed at the air outlet that is symmetrical to the acoustic environment of the air inlet. When the impeller rotates, the noise waves generated at the air inlet and the air cutter with opposite phases interfere with each other and cancel each other out, avoiding the relative superposition of noise from the air intake and exhaust. Furthermore, the gap between the air cutter and the fan blades allows the broadband noise passing through the fan blades to be converted into high-frequency sound waves that are easy to absorb. Thus, while ensuring the air volume, the noise can be self-cancelled inside the casing, thereby suppressing noise.

[0008] Preferably, the distance between the fan blade and the air inlet is 13mm to 20mm.

[0009] After the airflow passes through the air inlet, there is enough distance for the turbulent flow to become stable and flow to the fan blades, avoiding the fluctuation of the fan blades due to uneven air intake, and reducing the generation of airflow separation noise and rotational stall noise.

[0010] The distance between the fan blade and the air inlet is H, the axial length of the air cutter is h, and the ratio of H to h is 1:1-1.3.

[0011] Preferably, the distance between the fan blade and the air inlet is 14mm, and the axial length of the air cutter is 14mm.

[0012] Preferably, the airflow from the air inlet to the fan blade is the first aerodynamic environment, and the airflow from the fan blade to the air outlet is the second aerodynamic environment. The static pressure distribution, air intake angle of attack, and airflow velocity of the first and second aerodynamic environments are consistent and stable, thereby making the Helmholtz resonance cavity formed at the air inlet and the air cutter highly matched in spectrum and phase when the impeller rotates, thus producing a sound wave interference cancellation effect and weakening the noise energy.

[0013] Preferably, the number of fan blades is greater than 5 and is coprime to the number of air-cutting ribs in the housing, so that when the impeller rotates, the periodic pulsations generated when any impeller passes over the air-cutting ribs will not be synchronously superimposed, thereby achieving the purpose of eliminating resonance noise.

[0014] The number of the cutting ribs can be greater than the number of the fan blades, or it can be less than the number of the fan blades.

[0015] Preferably, the fan blades have an arc-shaped structure, which delays vortex shedding and improves flow guiding efficiency.

[0016] Preferably, the air cutter has an arc-shaped structure, which reduces flow resistance and allows airflow to flow along the surface of the air cutter, ensuring basic air volume and air outlet effect.

[0017] Preferably, the fan blades and the air-cutting ribs have opposite curvatures, thereby actively counteracting the rotational momentum of the airflow.

[0018] Compared with the prior art, the beneficial effects of this utility model are:

[0019] By setting the cavity structure at the air inlet and outlet to the same length, a Helmholtz resonance cavity is formed at the air inlet and the air cutter. When the impeller rotates, the aerodynamic noise generated at the air inlet and the air outlet is highly matched in terms of spectrum and phase. This causes the noise excited at the air inlet and the air cutter to form a phase-cancelling Helmholtz resonance pair, which actively cancels the noise energy. Furthermore, by designing the number of fan blades and air cutters to be mutually prime, periodic resonance is eliminated, thereby eliminating resonance noise. This achieves relatively low noise for the fan module while ensuring that the air volume is not reduced.

[0020] By limiting the axial position of the impeller and controlling the distance between the impeller and the air inlet or outlet, the interaction between the high-speed rotating blade tips and the narrow holes formed by the protective grille is avoided, thereby controlling the formation of frequency noise from the blades. Furthermore, by designing the number of blades and the air-cutting ribs to be mutually prime, periodic resonance is eliminated, thereby eliminating resonance noise. This achieves relatively low noise for the fan module while ensuring that the air volume is not reduced. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the overall structure of a low-noise fan module according to the present invention;

[0022] Figure 2 This is a structural schematic diagram of the present invention from another angle;

[0023] Figure 3 This is a three-dimensional sectional view of the housing of this utility model from a side sectional reference.

[0024] Figure 4 This is a schematic diagram of the axial cross-sectional structure of this utility model.

[0025] Reference numerals: 1. Shell; 2. Impeller; 3. Air cutter; 11. Air inlet; 12. Air outlet; 21. Fan blade. Detailed Implementation

[0026] The present invention will now be further described with reference to the accompanying drawings and specific embodiments.

[0027] like Figure 1 — Figure 4 As shown, this embodiment discloses a low-noise fan module. The low-noise fan module provided in this embodiment has a long cylindrical head structure, including an air duct formed by a housing 1, an impeller 2 disposed in the middle section of the air duct, and a drive unit (not shown in the figure) for driving the impeller 2. The axial front end of the impeller 2 corresponds to the air inlet 11 of the air duct, and the axial rear end corresponds to the air outlet 12 of the air duct. A wind-cutting rib 3 is disposed inside the air outlet 12, and the wind-cutting rib 3 and the fan blade 21 of the impeller 2 maintain a clearance fit.

[0028] The axial length of the air-cutting rib 3 is equal to the distance between the fan blade 21 of the impeller 2 and the air inlet 11. The section from the air inlet 11 to the fan blade 21 is the first aerodynamic environment, and the section from the fan blade 21 to the air outlet 12 is the second aerodynamic environment. The static pressure distribution, air intake angle of attack, and airflow velocity of the first and second aerodynamic environments are consistent and stable, so that the air inlet 11 region and the air-cutting rib 3 region of the air outlet 12 form two acoustically symmetrical Helmholtz resonant cavities.

[0029] When the impeller 2 rotates, aerodynamic noise will be generated at the air inlet 11 and the air cutter 3 respectively. Due to the symmetry of the resonant cavity, the noise at these two locations is highly matched in terms of spectrum and phase but opposite in phase, which can generate a sound wave interference cancellation effect inside the housing 1, effectively canceling the noise energy and avoiding the superposition of air inlet and outlet noise.

[0030] The distance H between the fan blade 21 and the air inlet 11 is designed to be 14mm. Correspondingly, the axial length h of the air cutter 3 is also set to 14mm. This allows the airflow to have a sufficient stable section after entering the air inlet 11, so that the turbulent incoming flow tends to be stable before reaching the fan blade 21. This effectively avoids the force fluctuation of the fan blade 21 caused by uneven air intake, thereby reducing the generation of airflow separation noise and rotational stall noise.

[0031] The impeller 2 has 7 fan blades 21 and the housing 1 has 8 air-cutting ribs 3, which are coprime to the number of fan blades 21. When the impeller 2 rotates, only one fan blade 21 passes over the air-cutting rib 3, so that the periodic pressure pulsations generated by any fan blade 21 passing over the air-cutting rib 3 will not be synchronously superimposed, thereby achieving the purpose of dispersing and eliminating resonance noise.

[0032] Both the fan blade 21 and the air-cutting rib 3 have an arc-shaped structure. The arc of the fan blade 21 is opposite to the arc of the air-cutting rib 3, which is used to actively counteract the rotational momentum of the airflow.

[0033] Actual measurements showed that the wind speed at 5cm from the air outlet of this embodiment was 12.8m / s with a handheld anemometer, while the wind speed at 5cm from the air outlet of a traditional high-speed fan was 7.7m / s. The noise level detected by the handheld noise meter at 30cm from the air outlet of this embodiment was 73.2dB, while that of the traditional high-speed fan was 72.8dB.

Claims

1. A low-noise fan module, comprising a long cylindrical head structure, the head structure including an air duct formed by a housing, an impeller disposed within the air duct, and a drive unit for driving the impeller, characterized in that: The impeller is located in the middle section of the housing. The front end of the impeller corresponds to the air inlet of the air duct, and the rear end of the impeller corresponds to the air outlet of the air duct. The air outlet is provided with a cutting bristle that fits with the fan blades of the impeller. The axial length of the cutting bristle is equal to the distance between the fan blades and the air inlet so that the two ends of the impeller are at a certain distance from the air inlet and the air outlet.

2. The low-noise fan module according to claim 1, characterized in that: The distance between the fan blades and the air inlet is 13mm to 20mm.

3. A low-noise fan module according to claim 2, characterized in that: The distance between the fan blade and the air inlet is H, the axial length of the air cutter is h, and the ratio of H to h is 1:1-1.

3.

4. A low-noise fan module according to claim 3, characterized in that: The distance between the fan blade and the air inlet is 14mm, and the axial length of the air cutter is 14mm.

5. A low-noise fan module according to claim 1, 2, 3, or 4, characterized in that: The airflow from the air inlet to the fan blade is the first aerodynamic environment, and the airflow from the fan blade to the air outlet is the second aerodynamic environment. The static pressure distribution, air intake angle of attack, and airflow velocity of the first aerodynamic environment and the second aerodynamic environment are consistent and stable.

6. A low-noise fan module according to claim 5, characterized in that: The number of fan blades is greater than 5 and is coprime to the number of air-cutting ribs in the housing.

7. A low-noise fan module according to claim 6, characterized in that: The fan blades have an arc-shaped structure.

8. A low-noise fan module according to claim 7, characterized in that: The cutting edge has an arc-shaped structure.

9. A low-noise fan module according to claim 8, characterized in that: The fan blades and the cutting ribs have opposite curvatures.

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