CN211423009U - Frequency-adjustable noise-reducing centrifugal ventilator and volute thereof - Google Patents
Frequency-adjustable noise-reducing centrifugal ventilator and volute thereof Download PDFInfo
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- CN211423009U CN211423009U CN201921528834.4U CN201921528834U CN211423009U CN 211423009 U CN211423009 U CN 211423009U CN 201921528834 U CN201921528834 U CN 201921528834U CN 211423009 U CN211423009 U CN 211423009U
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- 238000010521 absorption reaction Methods 0.000 claims abstract description 73
- 238000005192 partition Methods 0.000 claims description 11
- 239000000463 material Substances 0.000 claims description 6
- 239000012814 acoustic material Substances 0.000 claims description 4
- 239000011491 glass wool Substances 0.000 claims description 3
- 230000000694 effects Effects 0.000 abstract description 11
- 230000007547 defect Effects 0.000 description 3
- 239000011358 absorbing material Substances 0.000 description 2
- 230000008030 elimination Effects 0.000 description 2
- 238000003379 elimination reaction Methods 0.000 description 2
- 230000030279 gene silencing Effects 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 230000035515 penetration Effects 0.000 description 1
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Abstract
The utility model discloses a volute of a frequency-adjustable noise-reducing centrifugal ventilator, which comprises a front cover plate, a rear cover plate, a middle surrounding plate and a volute tongue, wherein the middle surrounding plate is used for connecting the front cover plate and the rear cover plate, the volute tongue is positioned at the airflow outlet of the middle surrounding plate, the front cover plate, the rear cover plate and the middle surrounding plate surround an airflow channel, the volute tongue comprises a volute tongue inner wall and a volute tongue outer wall which are parallel to each other and are arranged at intervals, a plurality of resonant cavities are arranged between the volute tongue inner wall and the volute tongue outer wall, the volute tongue inner wall comprises a volute tongue front section inner wall and a volute tongue rear section inner wall, and the volute tongue outer wall comprises a; the inner walls of the front section and the rear section of the volute tongue are provided with sound absorption holes communicated with the airflow channel, and each resonant cavity at least comprises one sound absorption hole. When sound is transmitted to pass through the volute tongue with larger impact, sound waves enter the resonant cavity through the sound absorption hole to generate resonance in the resonant cavity, and the noise in the cavity is lost through continuous collision and friction, so that the sound absorption and noise reduction effects are achieved.
Description
Technical Field
The utility model relates to a spiral case, especially a centrifugal fan's that can make an uproar falls in adjustable frequency spiral case.
The utility model relates to a centrifugal fan, especially a but centrifugal fan that frequency modulation was fallen and is made an uproar.
Background
Because of its characteristics of large wheel diameter ratio, small size, high pressure coefficient and low noise, the multi-blade centrifugal ventilator is widely used in various low-pressure ventilation occasions such as air conditioners, dehumidifiers, smoke ventilators and the like. Along with the improvement of the life quality of people and the forced implementation of the national noise standard of household appliances, more rigorous requirements are provided for the high performance and low noise of the multi-blade centrifugal ventilator.
The multi-blade centrifugal ventilator mainly consists of a current collector, an impeller and a volute. The volute is one of three main components of a multi-blade centrifugal fan and is mainly used for collecting gas flowing out of an impeller and converting partial kinetic energy of the gas into static pressure energy, and the influence of the structure on the aeroacoustic performance of the fan cannot be ignored. Research shows that the flow unevenness in the volute of the multi-blade centrifugal fan is closely related to the aerodynamic performance, particularly the noise characteristic of the fan. Therefore, the axial flow condition in the volute of the centrifugal ventilator is deeply researched, and the centrifugal ventilator has a profound significance for improving the pneumatic performance of the fan and reducing the noise of the fan.
The noise sources of centrifugal ventilators mainly include three main categories: aerodynamic noise, electromagnetic noise, and mechanical noise. Aerodynamic noise, which can be divided into broadband noise and discrete noise, dominates the noise of the fan, wherein the blade pass frequency of the discrete noise and its harmonic noise are determined by the fan speed and increase with the increase of the fan speed. Therefore, when the ventilator operates under multiple working conditions such as variable rotating speed, the discrete frequency generated by the ventilator changes along with the rotating speed and changes in a frequency band.
The Helmholtz resonator is a noise reduction and elimination structure, has a simple structure, can control medium and high-quality noises, but has the defects that the Helmholtz resonator can only absorb noises with single frequency, has narrow silencing bandwidth, is not suitable for ventilators under multi-working-condition operation, and once the working condition is changed, the frequency of the noises and the silencing frequency become mismatched, so that the silencing effect is influenced. Therefore, the frequency of the control noise of the volute of the existing centrifugal ventilator has no adjustability or poor adjustability, the effective sound absorption broadband is limited, the noise frequency is inconvenient to adjust, the requirement on the structure size is high, and the volute is not beneficial to large-scale popularization.
For a centrifugal ventilator, it is very important to provide a frequency-adjustable noise-reduction centrifugal ventilator volute which is structurally satisfactory and is suitable for operating under working conditions such as variable rotating speed and the like.
Disclosure of Invention
In order to overcome the defects of the prior art, the utility model provides a can realize falling the spiral case of centrifugal fan who makes an uproar.
The utility model provides a technical scheme that its technical problem adopted is: a volute of a frequency-adjustable noise-reducing centrifugal ventilator comprises a front cover plate, a rear cover plate, a middle surrounding plate and a volute tongue, wherein the middle surrounding plate is used for connecting the front cover plate and the rear cover plate, the volute tongue is positioned at an airflow outlet of the middle surrounding plate, the front cover plate, the rear cover plate and the middle surrounding plate surround an airflow channel, the volute tongue comprises a volute tongue inner wall and a volute tongue outer wall which are parallel to each other and are arranged at intervals, a plurality of resonant cavities are arranged between the volute tongue inner wall and the volute tongue outer wall, the volute tongue inner wall comprises a volute tongue front section inner wall which is connected with the middle surrounding plate and is curved in a cambered surface shape, and a volute tongue rear section inner wall which is connected with the volute tongue front section inner wall, the volute tongue outer wall comprises a volute tongue front section outer wall corresponding to the;
the inner walls of the front section and the rear section of the volute tongue are provided with sound absorption holes communicated with the airflow channel, and each resonant cavity at least comprises one sound absorption hole.
The utility model has the advantages that: a Helmholtz resonance sound absorption principle is adopted at the volute tongue of the centrifugal ventilator volute, the structure of an original main noise source is optimized, and a resonant cavity consisting of the inner wall of the porous volute tongue and the outer wall of the volute tongue is adopted, so that the stability of airflow near the volute tongue is improved. When sound is transmitted to the volute tongue with larger impact, sound waves enter the resonant cavity through the sound absorption hole, the natural frequency of the resonant cavity is close to the noise frequency in the volute, resonance is generated in the resonant cavity, and the noise in the cavity is lost through continuous collision and friction, so that the sound absorption and noise reduction effects are achieved.
Further setting the following steps: the resonant cavity positioned on the inner wall of the front section of the volute tongue is a front-section resonant cavity, the resonant cavity positioned on the inner wall of the rear section of the volute tongue is a rear-section resonant cavity, and each front-section resonant cavity is internally provided with a secondary sound source which is arranged on the outer wall of the front section of the volute tongue; the secondary sound source is a loudspeaker, and the loudspeaker is arranged towards the inside of the front section resonant cavity. Through adjusting the frequency of the vibrating diaphragm on the loudspeaker, the sound absorption frequency of the volute is improved, the volume of the fan is not required to be increased, the noise reduction and sound absorption effects are exerted to a greater extent, and the reasonable operation range of the low-noise centrifugal fan is expanded. In order to improve the efficiency, a control device for adjusting the working frequency of the loudspeaker can be arranged, and a closed feedback adjusting system is additionally arranged, so that the purpose of autonomous frequency modulation and noise reduction is achieved.
Further setting the following steps: the resonant cavity between the inner wall of the volute tongue and the outer wall of the volute tongue is formed by separating a plurality of axial partition plates and radial partition plates which are perpendicular to each other, the axial partition plates are arranged along the axial direction of the volute, and the radial partition plates are arranged along the radial direction of the volute. The structure optimizes the distribution of resonant cavities and improves the noise reduction effect.
Further setting the following steps: the number of the resonant cavities at the inner wall of the front section of the volute tongue is more than or equal to 3, and the number of the resonant cavities at the inner wall of the rear section of the volute tongue is 1. Further optimize the distribution of resonant cavity, and improve the noise reduction effect.
Further setting the following steps: the sound absorption hole is of a straight-tube structure and is arranged perpendicular to the surface of the inner wall of the volute, and the sound absorption hole is circular or square; the distance between two adjacent sound absorption holes is the same, and the distance is 4-8 times of the aperture of the sound absorption hole. And the distribution of resonant cavities is further optimized, and the noise reduction effect is improved.
Further setting the following steps: the depth of the sound absorption hole is lcThe diameter of the sound absorption hole is dcWherein the aspect ratio of the depth to the diameter is lc/dcThe cross-sectional area of the sound absorption hole is S, and the area of the inner wall of the front section of the volute tongue or the inner wall of the rear section of the volute tongue is S0The perforation rate is P ═ S/S0Then, then
0.3＜lc/dc＜0.9；
10％＜P＝S/S0＜30％；
The cross section area of the sound absorption hole on the inner wall of the front section of the volute tongue is S1The cross section area of the sound absorption hole on the inner wall of the rear section of the volute tongue is S2The area of the inner wall of the front section of the volute tongue is S01The area of the inner wall of the rear section of the volute tongue is S,2Then (S)1/S01)＞(S2/S02). Through the restriction to the relations such as draw ratio and perforation rate, optimize sound absorbing structure, realize the best noise reduction and noise elimination effect.
Further setting the following steps: the length-diameter ratio of the sound absorption holes in the inner wall of the front section of the volute tongue is 2-4 times that of the sound absorption holes in the inner wall of the rear section of the volute tongue.
Further setting the following steps: the inboard of middle bounding wall covers there is the one deck acoustic absorption circle, and this acoustic absorption circle is including the acoustic material who makes an uproar, and acoustic material's thickness is 4 ~ 8 times of middle bounding wall thickness. The laying of the sound absorption material reduces the impact loss to the volute when the airflow flows into the volute flow channel from the impeller, has wide application range and improves the noise reduction effect.
Further setting the following steps: the sound absorption material is heat-resistant glass wool. And optimizing the sound absorption and noise reduction effects.
In order to overcome the defects of the prior art, the utility model provides a centrifugal fan that can realize making an uproar falls.
The utility model provides a technical scheme that its technical problem adopted is: a frequency-adjustable noise-reducing centrifugal fan comprises a volute, wherein the volute is the volute.
The utility model has the advantages that: a Helmholtz resonance sound absorption principle is adopted at the volute tongue of the centrifugal ventilator volute, the structure of an original main noise source is optimized, and a resonant cavity consisting of the inner wall of the porous volute tongue and the outer wall of the volute tongue is adopted, so that the stability of airflow near the volute tongue is improved. When sound is transmitted to the volute tongue with larger impact, sound waves enter the resonant cavity through the sound absorption hole, the natural frequency of the resonant cavity is close to the noise frequency in the volute, resonance is generated in the resonant cavity, and the noise in the cavity is lost through continuous collision and friction, so that the sound absorption and noise reduction effects are achieved.
Drawings
Fig. 1 is a schematic structural diagram of a first embodiment of the present invention.
Fig. 2 is a cross-sectional view of a first embodiment of the present invention.
Fig. 3 is an enlarged view of a portion a of fig. 2.
Fig. 4 is an enlarged view of a portion B of fig. 2.
Fig. 5 is a schematic structural view of a volute tongue according to an embodiment of the present invention.
Fig. 6 is a schematic structural view of another view angle of a volute tongue according to an embodiment of the present invention.
Fig. 7 is a partial sectional view of a volute tongue according to an embodiment of the present invention.
Fig. 8 is a partial perspective view of a volute tongue according to an embodiment of the present invention, where the inner wall of the front section of the volute tongue and the outer wall of the front section of the volute tongue are located.
The sound absorption structure comprises a middle enclosing plate 1, a front cover plate 2, a rear cover plate 3, a volute tongue 4, a volute tongue front section inner wall 411, a volute tongue rear section inner wall 412, a volute tongue front section outer wall 421, a volute tongue rear section outer wall 422, a front section resonant cavity 431, a rear section resonant cavity 432, a sound absorption hole 44, a loudspeaker 45, an axial partition plate 461, a radial partition plate 462, a sound absorption ring 5, a sound absorption material 51, a wire mesh 52 and a current collector 6.
Detailed Description
The invention will be further described with reference to the accompanying drawings:
the first embodiment is as follows: as shown in fig. 1 to 8, the present embodiment includes a front cover plate 2, a rear cover plate 3, a middle surrounding plate 1 for connecting the front cover plate 2 and the rear cover plate 3, and a volute tongue 4 located at an airflow outlet of the middle surrounding plate 1, the front cover plate 2, the rear cover plate 3 and the middle surrounding plate 1 form an airflow channel, and a current collector 6 is installed at an airflow inlet of the volute. The volute tongue 4 comprises a volute tongue inner wall and a volute tongue outer wall which are parallel to each other and arranged at intervals, a plurality of resonant cavities are arranged between the volute tongue inner wall and the volute tongue outer wall, the volute tongue inner wall comprises a volute tongue front section inner wall 411 which is connected with the middle enclosing plate 1 and is curved in an arc surface, and a volute tongue rear section inner wall 412 which is connected with the volute tongue front section inner wall 411, and the volute tongue outer wall comprises a volute tongue front section outer wall 421 corresponding to the volute tongue front section inner wall 411 and a volute tongue rear section outer wall 422 corresponding to the volute tongue rear section inner wall 412. The inner wall 411 of the front section of the volute tongue and the inner wall 412 of the rear section of the volute tongue are both provided with sound absorption holes 44 communicated with the airflow channel, and each resonant cavity at least comprises one sound absorption hole 44. The resonant cavity at the inner wall 411 of the front section of the volute tongue is a front-section resonant cavity 431, the resonant cavity at the inner wall 412 of the rear section of the volute tongue is a rear-section resonant cavity 432, and each front-section resonant cavity 431 is provided with a secondary sound source which is arranged on the outer wall 421 of the front section of the volute tongue; the secondary sound source is a speaker 45, and the speaker 45 is disposed toward the inside of the front-stage resonant cavity 431. In addition, although the left and right sides of the inner wall and the outer wall of the volute tongue are not sealed in fig. 5 and 6, as shown in fig. 1, the two openings are actually sealed by the front cover plate 2 and the rear cover plate 3, which is similar to the connection of the left and right sides of the middle enclosing plate 1, so that the space between the inner wall and the outer wall of the volute tongue forms a substantially closed chamber.
The resonant cavity between the inner wall of the volute tongue and the outer wall of the volute tongue is formed by separating a plurality of axial baffles 461 and radial baffles 462 which are perpendicular to each other, as shown in the figure, the axial baffles 461 are arranged along the axial direction of the volute, and the radial baffles 462 are arranged along the radial direction of the volute. The volute axis direction refers to a direction perpendicular to the paper in fig. 2, and the volute radial direction refers to a direction perpendicular to the volute axis direction in fig. 2, while the structure in fig. 7 can be referred to. Referring to fig. 5 to 7, the number of resonant cavities at the inner wall 411 of the front section of the volute tongue is 9, and the number of resonant cavities at the inner wall 412 of the rear section of the volute tongue is divided into 3 by the radial partition 462. Further optimize the distribution of resonant cavity, and improve the noise reduction effect. The sound absorption hole 44 is of a straight-tube structure and is perpendicular to the inner wall surface of the volute, and the shape of the sound absorption hole 44 is circular or square; the distance between two adjacent sound-absorbing holes 44 is the same, and the distance is 4 times of the aperture of the sound-absorbing hole 44.
In this embodiment, the sound absorption hole 44 has a depth of lcThe diameter of the sound-absorbing hole 44 is dcWherein the aspect ratio of the depth to the diameter is lc/dcThe cross-sectional area of the sound absorption hole 44 is S, and the area of the inner wall 411 of the front section of the volute tongue or the inner wall 412 of the rear section of the volute tongue is S0The perforation rate is P ═ S/S0Then, then
0.3＜lc/dc＜0.9；
10％＜P＝S/S0＜30％；
The cross-sectional area of the sound absorption hole on the inner wall 411 of the front section of the volute tongue is S1The cross-sectional area of the sound absorption hole 44 on the inner wall 412 of the rear section of the volute tongue is S2The area of the inner wall 411 of the front section of the volute tongue is S01The area of the inner wall 412 of the rear section of the volute tongue is S,2When the penetration rate is S at 411 on the anterior segment of the volute tongue1/S01) The perforation rate at the inner wall 412 of the rear section of the volute tongue is (S)2/S02)，(S1/S01)＞(S2/S02) And the length-diameter ratio of the sound absorption hole 44 at the inner wall 411 of the front section of the volute tongue is 2 times of the length-diameter ratio of the sound absorption hole 44 at the inner wall 412 of the rear section of the volute tongue. At this time, it is fixedThe diameter of the sound absorption hole on the inner wall 411 of the anterior segment of the cochlear tongue is dc1Diameter d of sound-absorbing hole on inner wall 412 of rear section of volute tonguec2. As shown in fig. 5 to 7, a layer of sound absorption ring 5 covers the inner side of the middle coaming 1, the sound absorption ring 5 comprises a noise reduction sound absorption material 51, and the sound absorption material 51 is fixed on the inner side wall of the middle coaming 1 through a wire mesh 52. The sound absorbing material 51 is heat-resistant glass wool, and the thickness of the sound absorbing material 51 is 4 times of the thickness of the middle shroud 1.
In this embodiment, the sound absorption hole 44 has a depth of lc2mm, the diameter d of the sound absorption hole on the inner wall 411 of the front segment of the volute tonguec14mm, the diameter d of the sound absorption hole on the inner wall 412 of the rear section of the volute tonguec28mm, the length-diameter ratio of the sound absorption hole 44 at the inner wall 411 of the front section of the volute tongue is 2/4, and the length-diameter ratio of the sound absorption hole 44 at the inner wall 412 of the rear section of the volute tongue is 2/8. The number of the sound absorption holes at the inner wall 411 of the front section of the volute tongue is 174, and the number of the sound absorption holes at the inner wall 412 of the rear section of the volute tongue is 84. The width of the volute tongue is 200mm, the curvature radius of the inner wall 411 of the front section of the volute tongue is 30mm, the length of the inner wall 412 of the rear section of the volute tongue is 150mm, and the perforation rate at the inner wall 411 of the front section of the volute tongue is (S)1/S01) 0.176, and a perforation rate (S) at the inner wall 412 of the rear section of the volute tongue2/S02) Is 0.141, (S)1/S01)＞(S2/S02)。
In the experimental environment, by comparing the conventional volute and the volute of the present embodiment, the following comparison table was obtained.
TABLE 1
Simultaneously, discover after a large amount of contrast experiments in the laboratory, this embodiment is compared traditional centrifugal fan, effectively falls to make an uproar and is greater than 8% to the noise, has improved centrifugal fan's operational environment greatly.
Example two: the present embodiment is a centrifugal fan that employs the scroll casing disclosed in the first embodiment.
Claims (10)
1. The utility model provides a but spiral case of centrifugal fan of making an uproar falls in frequency modulation, includes front shroud, back shroud, is used for connecting the middle bounding wall of front shroud and back shroud, and is located the spiral tongue of middle bounding wall air current exit, and front shroud, back shroud and middle bounding wall enclose airflow channel, characterized by: the volute tongue comprises a volute tongue inner wall and a volute tongue outer wall which are parallel to each other and are arranged at intervals, a plurality of resonant cavities are arranged between the volute tongue inner wall and the volute tongue outer wall, the volute tongue inner wall comprises a volute tongue front section inner wall which is connected with the middle enclosing plate and is curved in a cambered surface shape, and a volute tongue rear section inner wall which is connected with the volute tongue front section inner wall, and the volute tongue outer wall comprises a volute tongue front section outer wall corresponding to the volute tongue front section inner wall and a volute tongue rear section outer wall corresponding to the volute tongue rear section inner wall;
the inner walls of the front section and the rear section of the volute tongue are provided with sound absorption holes communicated with the airflow channel, and each resonant cavity at least comprises one sound absorption hole.
2. A volute for a centrifugal fan having frequency and noise reduction capabilities as defined in claim 1 wherein: the resonant cavity positioned on the inner wall of the front section of the volute tongue is a front-section resonant cavity, the resonant cavity positioned on the inner wall of the rear section of the volute tongue is a rear-section resonant cavity, and each front-section resonant cavity is internally provided with a secondary sound source which is arranged on the outer wall of the front section of the volute tongue; the secondary sound source is a loudspeaker, and the loudspeaker is arranged towards the inside of the front section resonant cavity.
3. A volute for a centrifugal fan having frequency and noise reduction capabilities as defined in claim 1 wherein: the resonant cavity between the inner wall of the volute tongue and the outer wall of the volute tongue is formed by separating a plurality of axial partition plates and radial partition plates which are perpendicular to each other, the axial partition plates are arranged along the axial direction of the volute, and the radial partition plates are arranged along the radial direction of the volute.
4. A volute for a centrifugal fan having frequency and noise reduction capabilities as defined in claim 3 wherein: the number of the resonant cavities at the inner wall of the front section of the volute tongue is more than or equal to 3, and the number of the resonant cavities at the inner wall of the rear section of the volute tongue is 1.
5. A volute for a centrifugal fan having frequency and noise reduction capabilities as defined in claim 1 wherein: the sound absorption hole is of a straight-tube structure and is arranged perpendicular to the surface of the inner wall of the volute, and the sound absorption hole is circular or square; the distance between two adjacent sound absorption holes is the same, and the distance is 4-8 times of the aperture of the sound absorption hole.
6. A volute for a centrifugal fan with frequency and noise reduction according to any of claims 1 to 5, wherein: the depth of the sound absorption hole is lcThe diameter of the sound absorption hole is dcWherein the aspect ratio of the depth to the diameter is lc/dcThe cross-sectional area of the sound absorption hole is S, and the area of the inner wall of the front section of the volute tongue or the inner wall of the rear section of the volute tongue is S0The perforation rate is P ═ S/S0Then, then
0.3＜lc/dc＜0.9；
10％＜P＝S/S0＜30％；
The cross section area of the sound absorption hole on the inner wall of the front section of the volute tongue is S1The cross section area of the sound absorption hole on the inner wall of the rear section of the volute tongue is S2The area of the inner wall of the front section of the volute tongue is S01The area of the inner wall of the rear section of the volute tongue is S,2Then (S)1/S01)＞(S2/S02)。
7. A volute for a centrifugal ventilator having frequency modulation and noise reduction in accordance with claim 6, wherein: the length-diameter ratio of the sound absorption holes in the inner wall of the front section of the volute tongue is 2-4 times that of the sound absorption holes in the inner wall of the rear section of the volute tongue.
8. A volute for a centrifugal fan having frequency and noise reduction capabilities as defined in claim 1 wherein: the inboard of middle bounding wall covers there is the one deck acoustic absorption circle, and this acoustic absorption circle is including the acoustic material who makes an uproar, and acoustic material's thickness is 4 ~ 8 times of middle bounding wall thickness.
9. A volute for a centrifugal fan having frequency and noise reduction capabilities as defined in claim 8 wherein: the sound absorption material is heat-resistant glass wool.
10. The utility model provides a centrifugal fan that can frequency modulation fall and make an uproar, including the spiral case, characterized by: the volute is the volute of claims 1-9.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
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| CN201921438232X | 2019-08-30 | ||
| CN201921438232 | 2019-08-30 |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110925240A (en) * | 2019-09-13 | 2020-03-27 | 浙江理工大学上虞工业技术研究院有限公司 | Frequency-adjustable noise-reducing centrifugal ventilator and volute thereof |
| CN113738664A (en) * | 2021-09-15 | 2021-12-03 | 杭州帅丰科技有限公司 | Noise reduction fan |
| CN114483644A (en) * | 2020-11-12 | 2022-05-13 | 佛山市顺德区美的洗涤电器制造有限公司 | Centrifugal impeller, centrifugal fan and range hood |
-
2019
- 2019-09-13 CN CN201921528834.4U patent/CN211423009U/en active Active
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110925240A (en) * | 2019-09-13 | 2020-03-27 | 浙江理工大学上虞工业技术研究院有限公司 | Frequency-adjustable noise-reducing centrifugal ventilator and volute thereof |
| CN114483644A (en) * | 2020-11-12 | 2022-05-13 | 佛山市顺德区美的洗涤电器制造有限公司 | Centrifugal impeller, centrifugal fan and range hood |
| CN114483644B (en) * | 2020-11-12 | 2024-03-26 | 佛山市顺德区美的洗涤电器制造有限公司 | Centrifugal impeller, centrifugal fan and fume absorbing equipment |
| CN113738664A (en) * | 2021-09-15 | 2021-12-03 | 杭州帅丰科技有限公司 | Noise reduction fan |
| CN113738664B (en) * | 2021-09-15 | 2024-04-02 | 杭州帅丰科技有限公司 | Noise reduction fan |
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