US20190293090A1 - Airflow generator - Google Patents
Airflow generator Download PDFInfo
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- US20190293090A1 US20190293090A1 US16/158,138 US201816158138A US2019293090A1 US 20190293090 A1 US20190293090 A1 US 20190293090A1 US 201816158138 A US201816158138 A US 201816158138A US 2019293090 A1 US2019293090 A1 US 2019293090A1
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- United States
- Prior art keywords
- plate
- accommodating space
- bypass opening
- airflow generator
- airflow
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Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04D—NON-POSITIVE-DISPLACEMENT PUMPS
- F04D29/00—Details, component parts, or accessories
- F04D29/66—Combating cavitation, whirls, noise, vibration or the like; Balancing
- F04D29/661—Combating cavitation, whirls, noise, vibration or the like; Balancing especially adapted for elastic fluid pumps
- F04D29/663—Sound attenuation
- F04D29/665—Sound attenuation by means of resonance chambers or interference
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04D—NON-POSITIVE-DISPLACEMENT PUMPS
- F04D17/00—Radial-flow pumps, e.g. centrifugal pumps; Helico-centrifugal pumps
- F04D17/08—Centrifugal pumps
- F04D17/16—Centrifugal pumps for displacing without appreciable compression
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04D—NON-POSITIVE-DISPLACEMENT PUMPS
- F04D25/00—Pumping installations or systems
- F04D25/02—Units comprising pumps and their driving means
- F04D25/08—Units comprising pumps and their driving means the working fluid being air, e.g. for ventilation
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04D—NON-POSITIVE-DISPLACEMENT PUMPS
- F04D29/00—Details, component parts, or accessories
- F04D29/26—Rotors specially for elastic fluids
- F04D29/28—Rotors specially for elastic fluids for centrifugal or helico-centrifugal pumps for radial-flow or helico-centrifugal pumps
- F04D29/30—Vanes
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04D—NON-POSITIVE-DISPLACEMENT PUMPS
- F04D29/00—Details, component parts, or accessories
- F04D29/40—Casings; Connections of working fluid
- F04D29/42—Casings; Connections of working fluid for radial or helico-centrifugal pumps
- F04D29/4206—Casings; Connections of working fluid for radial or helico-centrifugal pumps especially adapted for elastic fluid pumps
- F04D29/4226—Fan casings
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04D—NON-POSITIVE-DISPLACEMENT PUMPS
- F04D29/00—Details, component parts, or accessories
- F04D29/66—Combating cavitation, whirls, noise, vibration or the like; Balancing
- F04D29/661—Combating cavitation, whirls, noise, vibration or the like; Balancing especially adapted for elastic fluid pumps
- F04D29/663—Sound attenuation
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04D—NON-POSITIVE-DISPLACEMENT PUMPS
- F04D29/00—Details, component parts, or accessories
- F04D29/66—Combating cavitation, whirls, noise, vibration or the like; Balancing
- F04D29/661—Combating cavitation, whirls, noise, vibration or the like; Balancing especially adapted for elastic fluid pumps
- F04D29/663—Sound attenuation
- F04D29/664—Sound attenuation by means of sound absorbing material
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04D—NON-POSITIVE-DISPLACEMENT PUMPS
- F04D29/00—Details, component parts, or accessories
- F04D29/26—Rotors specially for elastic fluids
- F04D29/28—Rotors specially for elastic fluids for centrifugal or helico-centrifugal pumps for radial-flow or helico-centrifugal pumps
- F04D29/281—Rotors specially for elastic fluids for centrifugal or helico-centrifugal pumps for radial-flow or helico-centrifugal pumps for fans or blowers
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04D—NON-POSITIVE-DISPLACEMENT PUMPS
- F04D29/00—Details, component parts, or accessories
- F04D29/40—Casings; Connections of working fluid
- F04D29/42—Casings; Connections of working fluid for radial or helico-centrifugal pumps
- F04D29/4206—Casings; Connections of working fluid for radial or helico-centrifugal pumps especially adapted for elastic fluid pumps
- F04D29/4213—Casings; Connections of working fluid for radial or helico-centrifugal pumps especially adapted for elastic fluid pumps suction ports
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
- F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
- F05D2260/00—Function
- F05D2260/96—Preventing, counteracting or reducing vibration or noise
Definitions
- the disclosure relates to an airflow generator, more particularly to an airflow generator having a muffling part.
- BPF noise blade passing frequency noise
- the airflow generator includes a casing, a fan blade and a muffling part.
- the casing has an air inlet, an air outlet, an accommodating space and a bypass opening connected to one another.
- the fan blade is disposed in the accommodating space.
- the muffling part is located outside the accommodating space and is disposed at the bypass opening.
- the muffling part has an airflow channel, and the airflow channel is connected to the accommodating space via the bypass opening.
- the fan blade is capable of sucking ambient air into the accommodating space via the air inlet so as to create an air current throughout the accommodating space and to force the air current to flow into the airflow channel via the bypass opening.
- FIG. 1 is a perspective view of an airflow generator according to a first embodiment of the disclosure
- FIG. 2 is a cross-sectional view of the airflow generator in FIG. 1 ;
- FIG. 3 is a schematic view showing how the muffling part in FIG. 1 reduces noise
- FIG. 4 is a cross-sectional view of an airflow generator according to a second embodiment of the disclosure.
- FIG. 1 is a perspective view of an airflow generator according to a first embodiment of the disclosure.
- FIG. 2 is a cross-sectional view of the airflow generator in FIG. 1 .
- the airflow generator 1 is, for example, a centrifugal fan and can be mounted in an electronic device such as a laptop computer.
- the airflow generator 1 includes a casing 10 , a fan blade 20 and a muffling part 40 .
- the casing 10 is made of a hard material such as a plastic material.
- the casing 10 has an air inlet 11 , an air outlet 12 , an accommodating space 13 and a bypass opening 14 connected to one another.
- the casing 10 includes a first plate 15 , a second plate 16 and a side wall 17 , and the first plate 15 and the second plate 16 are respectively connected to two opposite sides of the side wall 17 so as to form the accommodating space 13 and the air outlet 12 with the side wall 17 .
- the air inlet 11 is located on the first plate 15 .
- the bypass opening 14 is located on the side wall 17 .
- the bypass opening 14 divides the side wall 17 into a first wall section 171 and a second wall section 172 .
- the second wall section 172 includes a connecting portion 1721 and a tongue portion 1722 connected to each other.
- the connecting portion 1721 is located between and connected to the bypass opening 14 and the tongue portion 1722 .
- the fan blade 20 is disposed within the accommodating space 13 of the casing 10 . From the viewpoint of FIG. 2 , the fan blade 20 is able to be rotated in counter clockwise direction. As shown in FIG. 2 , the fan blade 20 is able to be rotated along a direction D, and during the rotation, each blade of the fan blade 20 can sequentially pass through the tongue portion 1722 , the connecting portion 1721 , the bypass opening 14 and the first wall section 171 . By this configuration, the fan blade 20 is able to suck ambient air into the accommodating space 13 via the air inlet 11 so as to create an air current throughout the accommodating space 13 and then discharge it via the air outlet 12 .
- the muffling part 40 is made of, for example, a hard material such as a plastic material.
- the muffling part 40 is disposed on the outer surface of the side wall 17 and covers the bypass opening 14 .
- the muffling part 40 is located outside the accommodating space 13 .
- the muffling part 40 is a hollow structure which has an airflow channel 41 connected to the bypass opening 14 .
- the airflow channel 41 is connected to the accommodating space 13 via the bypass opening 14 .
- the muffling part 40 includes a longer side plate 42 , a shorter side plate 43 , an upper plate 45 , a lower plate 46 and an end plate 44 .
- the longer side plate 42 includes an extension part 421 and a guiding part 422 .
- the longer side plate 42 , the shorter side plate 43 , the upper plate 45 , the lower plate 46 and the end plate 44 together form the airflow channel 41 , and the extension part 421 of the longer side plate 42 , the shorter side plate 43 , the upper plate 45 and the lower plate 46 are respectively connected to sides of the end plate 44 .
- the guiding part 422 of the longer side plate 42 , the shorter side plate 43 , the upper plate 45 and the lower plate 46 are respectively connected to edges of the bypass opening 14 .
- the guiding part 422 is a curved plate, and the muffling part 40 and the casing 10 have a smooth junction between the guiding part 422 and the connecting portion 1721 of the second wall section 172 that guides air current generated by the fan blade to flow into the airflow channel 41 via the bypass opening 14 .
- This helps to reduce the blade passing frequency noise (abbreviated to BPF noise) caused by the fan blade 20 .
- BPF noise blade passing frequency noise
- the blade passing frequency noise is mainly caused by the rotor-stator interaction.
- the shorter side plate 43 and the first wall section 171 are the same in curvature, thus the shorter side plate 43 can fit on the surface of the first wall section 171 .
- This configuration helps to decrease the overall volume of the airflow generator 1 , such that the airflow generator 1 is able to be mounted within a compact laptop computer.
- the shorter side plate 43 is optional.
- the muffling part may have no shorter side plate, and the airflow channel may be formed by the longer side plate, the first wall section, the upper plate, the lower plate and the end plate.
- FIG. 3 is a schematic view showing how the muffling part in FIG. 1 reduces noise.
- the airflow channel 41 of the muffling part 40 has a length L, and the length L is determined by the ‘blade passing frequency’ of the fan blade 20 .
- the length L is one fourth of the wavelength ⁇ of the blade passing frequency of the fan blade 20
- an incident wave 60 which is formed while the air current flowing into the airflow channel 41 can be reflected by the bottom of the muffling part 40 so as to produce a reflected wave 70 which has the same amplitude but has a phase opposite to the incident wave 60 .
- the incident wave 60 and the reflected wave 70 would interfere with each other, thereby reducing the noise which is caused by the blade passing frequency of the fan blade 20 .
- a reference line S is defined to pass through the rotating axis R of the fan blade 20 and to be perpendicular to a plane P where the air outlet 12 is located, and the muffling part 40 and the tongue portion 1722 are respectively located at two opposite sides of the reference line S.
- the blade passing frequency noise and the total noise are respectively 26.8 dB(A)/20 u Pa and 41.4 dB(A)/20 u Pa.
- the blade passing frequency noise and the total noise are respectively increased to 39.5 dB(A)/20 u Pa and 44.9 dB(A)/20 u Pa. Therefore, the configuration that the muffling part 40 and the tongue portion 1722 are disposed at opposite sides of the reference line S has a better effect in reducing noise.
- the reflected wave 70 is ensured to have the same amplitude as the incident wave 60 so as to completely eliminate the incident wave 60 .
- the muffling part may be made of a soft material such as a soft plastic material or a soft rubber material. As such, the muffling part is able to be deformed to change its shape, helping the airflow generator to fit in a laptop computer which has an irregular space.
- the airflow generator 1 further includes a porous member 50 located between the guiding part 422 and the bypass opening 14 .
- the porous member 50 is, for example, a sponge.
- the porous member 50 is able to reduce the turbulence occurring when the air current hitting a sharp part between the shorter side plate 43 and the first wall section 171 so as to reduce the noise caused by the turbulence.
- the porous member 50 has a plurality of pores 51 , and the pores 51 help the air current to flow into the muffling part 40 and also help to reduce the blade passing frequency noise.
- the total noise caused by the airflow generator 1 is approximately 40 dB(A)/20 u Pa and is smaller than that of the airflow generator without both of the muffling part 40 and the porous member 50 (e.g., 43.4 dB(A)/20 u Pa) and even smaller than that of the airflow generator only having the muffling part 40 (e.g., 41.1 dB(A)/20 u Pa).
- the porous member 50 helps to enhance the effect in reducing noise.
- the muffling part 40 is detachably mounted on the side wall 17 via screws or other fasteners. Therefore, the muffling part 40 can be detached from the casing 10 so that it is more convenient to clean dust therefrom.
- the fan blade 20 would deform when being used for in a long time, and the deformed fan blade 20 might be replaced with a new fan blade.
- the new fan blade may have a blade passing frequency different from the original fan blade.
- the muffling part 40 can be replaced with another muffling part having an airflow channel having a length equal to one fourth of the wavelength of the blade passing frequency of the new fan blade, thereby maintaining the effect of the noise reduction.
- the muffling part and the casing may be made of one piece to increase the airtightness level between the muffling part and the casing.
- the muffling part 40 is fixed at the side wall 17 , but the present disclosure is not limited thereto. In some other embodiments, the muffling part may be fixed at the first plate or the second plate of the casing.
- the type of the airflow generator 1 is not restricted.
- the airflow generator may be an axial fan.
- FIG. 4 is a cross-sectional view of an airflow generator according to a second embodiment of the disclosure.
- This embodiment provides a muffling part 40 ′ which is a long hollow rectangular tube protruding from a side of a casing 10 ′ and being connected to an accommodating space 13 ′ of the casing 10 ′.
- the muffling part 40 ′ has an airflow channel 41 ′ in a length of L 2 , and the length L 2 equals to one fourth of the wavelength of the blade passing frequency of the fan blade 20 ′.
- the muffling part 40 ′ also helps to reduce the noise.
- the airflow channel of the muffling part has a length equal to one fourth of the wavelength of the blade passing frequency of the fan blade, the incident wave and the reflected wave occurring while the air current flowing into the airflow channel can interfere with each other so as to reduce the noise caused by the airflow generator.
- the configuration that the muffling part and the tongue portion are disposed at opposite sides of the reference line, which passes through the rotating axis of the fan blade and is perpendicular to a plane where the air outlet is located, has a better effect in effect in reducing noise.
- the porous member is able to reduce the turbulence occurring when the air current hitting the sharp part between the shorter side plate and the first wall section so as to reduce the noise caused by the turbulence.
- the pores of the porous member help the air current to flow into the muffling part and also help to reduce the blade passing frequency noise.
- the muffling part is made of hard material, the reflected wave is ensured to have the same amplitude as the incident wave so as to completely eliminate the incident wave, thereby increasing the effect in reducing noise.
- the smooth junction between the guiding part and the connecting portion helps the air current generated by the fan blade to flow into the airflow channel.
- the muffling part may be made of soft material, such that the muffling part is able to be deformed to change its shape, helping the airflow generator to fit in a laptop computer which has an irregular space.
- the muffling part can be detached from the casing, thus it is more convenient to clean dust therefrom.
- the muffling part is able to be replaced by another muffling part having an airflow channel having a length equal to one fourth of the wavelength of the blade passing frequency of the new fan blade, thereby maintaining the effect of the noise reduction.
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Abstract
Description
- This non-provisional application claims priority under 35 U.S.C. § 119(a) on Patent Application No(s). 201810249200.9 filed in China on Mar. 22, 2018 the entire contents of which are hereby incorporated by reference.
- The disclosure relates to an airflow generator, more particularly to an airflow generator having a muffling part.
- As technology progresses, electronic devices, such as desktop computers, laptop computers or servers have a significant increase in performance, but it comes with a large amount of high-temperature heat. The high-temperature heat will increase the electronic device's running temperature and lower its performance. To prevent this, most of the electronic devices have a fan for heat dissipation.
- However, the interaction between the fan blade and the casing would cause a noise called blade passing frequency noise (abbreviated to BPF noise). Some change the shape of the fan blade or the shape of the airflow channel in order to eliminate such noise, but there is still no remarkable improvement.
- One embodiment of the disclosure provides an airflow generator. The airflow generator includes a casing, a fan blade and a muffling part. The casing has an air inlet, an air outlet, an accommodating space and a bypass opening connected to one another. The fan blade is disposed in the accommodating space. The muffling part is located outside the accommodating space and is disposed at the bypass opening. The muffling part has an airflow channel, and the airflow channel is connected to the accommodating space via the bypass opening. The fan blade is capable of sucking ambient air into the accommodating space via the air inlet so as to create an air current throughout the accommodating space and to force the air current to flow into the airflow channel via the bypass opening.
- The present disclosure will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only and thus are not limitative to the present disclosure and wherein:
-
FIG. 1 is a perspective view of an airflow generator according to a first embodiment of the disclosure; -
FIG. 2 is a cross-sectional view of the airflow generator inFIG. 1 ; -
FIG. 3 is a schematic view showing how the muffling part inFIG. 1 reduces noise; and -
FIG. 4 is a cross-sectional view of an airflow generator according to a second embodiment of the disclosure. - In the following detailed description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the disclosed embodiments. It will be apparent, however, that one or more embodiments may be practiced without these specific details. In other instances, well-known structures and devices are schematically shown in order to simplify the drawing.
- In addition, the following embodiments are disclosed by the figures, and some practical details are described in the following paragraphs, but the present disclosure is not limited thereto. Furthermore, for the purpose of illustration, some of the structures and components in the figures are simplified, and wires, reference lines or buses are omitted in some of the figures.
- Moreover, the terms used in the present disclosure, such as technical and scientific terms, have its own meanings and can be comprehended by those skilled in the art, unless the terms are additionally defined in the present disclosure. That is, the terms used in the following paragraphs should be read on the meaning commonly used in the related fields and will not be overly explained, unless the terms have a specific meaning in the present disclosure.
- Please refer to
FIG. 1 andFIG. 2 .FIG. 1 is a perspective view of an airflow generator according to a first embodiment of the disclosure.FIG. 2 is a cross-sectional view of the airflow generator inFIG. 1 . - This embodiment provides an
airflow generator 1. Theairflow generator 1 is, for example, a centrifugal fan and can be mounted in an electronic device such as a laptop computer. Theairflow generator 1 includes acasing 10, afan blade 20 and amuffling part 40. - The
casing 10 is made of a hard material such as a plastic material. Thecasing 10 has anair inlet 11, anair outlet 12, anaccommodating space 13 and a bypass opening 14 connected to one another. In detail, thecasing 10 includes afirst plate 15, asecond plate 16 and aside wall 17, and thefirst plate 15 and thesecond plate 16 are respectively connected to two opposite sides of theside wall 17 so as to form theaccommodating space 13 and theair outlet 12 with theside wall 17. Theair inlet 11 is located on thefirst plate 15. The bypass opening 14 is located on theside wall 17. The bypass opening 14 divides theside wall 17 into afirst wall section 171 and asecond wall section 172. Thesecond wall section 172 includes a connectingportion 1721 and atongue portion 1722 connected to each other. The connectingportion 1721 is located between and connected to the bypass opening 14 and thetongue portion 1722. - The
fan blade 20 is disposed within theaccommodating space 13 of thecasing 10. From the viewpoint ofFIG. 2 , thefan blade 20 is able to be rotated in counter clockwise direction. As shown inFIG. 2 , thefan blade 20 is able to be rotated along a direction D, and during the rotation, each blade of thefan blade 20 can sequentially pass through thetongue portion 1722, the connectingportion 1721, the bypass opening 14 and thefirst wall section 171. By this configuration, thefan blade 20 is able to suck ambient air into theaccommodating space 13 via theair inlet 11 so as to create an air current throughout theaccommodating space 13 and then discharge it via theair outlet 12. - In this embodiment, the
muffling part 40 is made of, for example, a hard material such as a plastic material. Themuffling part 40 is disposed on the outer surface of theside wall 17 and covers the bypass opening 14. In other words, themuffling part 40 is located outside theaccommodating space 13. In detail, themuffling part 40 is a hollow structure which has anairflow channel 41 connected to the bypass opening 14. Thus, theairflow channel 41 is connected to theaccommodating space 13 via the bypass opening 14. In more detail, themuffling part 40 includes alonger side plate 42, ashorter side plate 43, anupper plate 45, alower plate 46 and anend plate 44. Thelonger side plate 42 includes anextension part 421 and aguiding part 422. Thelonger side plate 42, theshorter side plate 43, theupper plate 45, thelower plate 46 and theend plate 44 together form theairflow channel 41, and theextension part 421 of thelonger side plate 42, theshorter side plate 43, theupper plate 45 and thelower plate 46 are respectively connected to sides of theend plate 44. The guidingpart 422 of thelonger side plate 42, theshorter side plate 43, theupper plate 45 and thelower plate 46 are respectively connected to edges of the bypass opening 14. - In this embodiment, the
guiding part 422 is a curved plate, and themuffling part 40 and thecasing 10 have a smooth junction between theguiding part 422 and the connectingportion 1721 of thesecond wall section 172 that guides air current generated by the fan blade to flow into theairflow channel 41 via the bypass opening 14. This helps to reduce the blade passing frequency noise (abbreviated to BPF noise) caused by thefan blade 20. It is noted that the blade passing frequency noise is mainly caused by the rotor-stator interaction. - Moreover, in this embodiment, the
shorter side plate 43 and thefirst wall section 171 are the same in curvature, thus theshorter side plate 43 can fit on the surface of thefirst wall section 171. This configuration helps to decrease the overall volume of theairflow generator 1, such that theairflow generator 1 is able to be mounted within a compact laptop computer. - However, the
shorter side plate 43 is optional. For example, in some other embodiments, the muffling part may have no shorter side plate, and the airflow channel may be formed by the longer side plate, the first wall section, the upper plate, the lower plate and the end plate. - The science behind the muffling
part 40 is described in the following paragraphs. - Please refer to
FIG. 3 .FIG. 3 is a schematic view showing how the muffling part inFIG. 1 reduces noise. Theairflow channel 41 of the mufflingpart 40 has a length L, and the length L is determined by the ‘blade passing frequency’ of thefan blade 20. When the length L is one fourth of the wavelength λ of the blade passing frequency of thefan blade 20, anincident wave 60 which is formed while the air current flowing into theairflow channel 41 can be reflected by the bottom of the mufflingpart 40 so as to produce a reflectedwave 70 which has the same amplitude but has a phase opposite to theincident wave 60. Theincident wave 60 and the reflectedwave 70 would interfere with each other, thereby reducing the noise which is caused by the blade passing frequency of thefan blade 20. For example, when the blade passing frequency of thefan blade 20 is 2145 Hz, the wavelength λ of the blade passing frequency of thefan blade 20 is equal to sound speed divided by frequency; that is, 342(m/s)/2145(Hz)=0.16(m). Therefore, the length L of theairflow channel 41 of the mufflingpart 40 is equal to one fourth of the wavelength λ; that is, 0.16(m)/4=0.04(m). - Then, to compare the
airflow generator 1 with one without the mufflingpart 40. An experiment result shows that the blade passing frequency noise and the total noise of the airflow generator without the mufflingpart 40 are respectively 35.6 dB(A)/20 u Pa and 43.4 dB(A)/20 u Pa, but those of theairflow generator 1 are respectively decreased to 26.8 dB(A)/20 u Pa and 41.4 dB(A)/20 u Pa. The total noise value means the sum of all the noise that caused by the airflow generator operating at a frequency range between 100 Hz and 20 kHz. Obviously, with the help of the mufflingpart 40, theairflow generator 1 has a significant effect in reducing noise. - Moreover, the following further discusses the relationship between the position of the muffling
part 40 and the effect of the noise reduction. As shown inFIG. 2 , a reference line S is defined to pass through the rotating axis R of thefan blade 20 and to be perpendicular to a plane P where theair outlet 12 is located, and the mufflingpart 40 and thetongue portion 1722 are respectively located at two opposite sides of the reference line S. In such a case, the blade passing frequency noise and the total noise are respectively 26.8 dB(A)/20 u Pa and 41.4 dB(A)/20 u Pa. In another case that the mufflingpart 40 and thetongue portion 1722 are located at the same side of the reference line S and the mufflingpart 40 is disposed on thetongue portion 1722, the blade passing frequency noise and the total noise are respectively increased to 39.5 dB(A)/20 u Pa and 44.9 dB(A)/20 u Pa. Therefore, the configuration that the mufflingpart 40 and thetongue portion 1722 are disposed at opposite sides of the reference line S has a better effect in reducing noise. - In addition, since the muffling
part 40 is made of hard material, the reflectedwave 70 is ensured to have the same amplitude as theincident wave 60 so as to completely eliminate theincident wave 60. - Furthermore, in some other embodiments, the muffling part may be made of a soft material such as a soft plastic material or a soft rubber material. As such, the muffling part is able to be deformed to change its shape, helping the airflow generator to fit in a laptop computer which has an irregular space.
- In this embodiment, the
airflow generator 1 further includes aporous member 50 located between the guidingpart 422 and thebypass opening 14. Theporous member 50 is, for example, a sponge. Theporous member 50 is able to reduce the turbulence occurring when the air current hitting a sharp part between theshorter side plate 43 and thefirst wall section 171 so as to reduce the noise caused by the turbulence. In addition, theporous member 50 has a plurality ofpores 51, and thepores 51 help the air current to flow into the mufflingpart 40 and also help to reduce the blade passing frequency noise. - Another experiment result shows that the total noise caused by the
airflow generator 1 is approximately 40 dB(A)/20 u Pa and is smaller than that of the airflow generator without both of the mufflingpart 40 and the porous member 50 (e.g., 43.4 dB(A)/20 u Pa) and even smaller than that of the airflow generator only having the muffling part 40 (e.g., 41.1 dB(A)/20 u Pa). Obviously, theporous member 50 helps to enhance the effect in reducing noise. - In this embodiment, the muffling
part 40 is detachably mounted on theside wall 17 via screws or other fasteners. Therefore, the mufflingpart 40 can be detached from thecasing 10 so that it is more convenient to clean dust therefrom. On the other hand, thefan blade 20 would deform when being used for in a long time, and thedeformed fan blade 20 might be replaced with a new fan blade. However, the new fan blade may have a blade passing frequency different from the original fan blade. In this case, the mufflingpart 40 can be replaced with another muffling part having an airflow channel having a length equal to one fourth of the wavelength of the blade passing frequency of the new fan blade, thereby maintaining the effect of the noise reduction. However, in some other embodiments, the muffling part and the casing may be made of one piece to increase the airtightness level between the muffling part and the casing. - In this embodiment, the muffling
part 40 is fixed at theside wall 17, but the present disclosure is not limited thereto. In some other embodiments, the muffling part may be fixed at the first plate or the second plate of the casing. - In addition, the type of the
airflow generator 1 is not restricted. In some other embodiments, the airflow generator may be an axial fan. - Furthermore, the present disclosure is not limited to the
above muffling part 40. Please refer toFIG. 4 .FIG. 4 is a cross-sectional view of an airflow generator according to a second embodiment of the disclosure. This embodiment provides a mufflingpart 40′ which is a long hollow rectangular tube protruding from a side of acasing 10′ and being connected to anaccommodating space 13′ of thecasing 10′. The mufflingpart 40′ has anairflow channel 41′ in a length of L2, and the length L2 equals to one fourth of the wavelength of the blade passing frequency of thefan blade 20′. Similarly, the mufflingpart 40′ also helps to reduce the noise. - According to the airflow generator as discussed above, since the airflow channel of the muffling part has a length equal to one fourth of the wavelength of the blade passing frequency of the fan blade, the incident wave and the reflected wave occurring while the air current flowing into the airflow channel can interfere with each other so as to reduce the noise caused by the airflow generator.
- In addition, the configuration that the muffling part and the tongue portion are disposed at opposite sides of the reference line, which passes through the rotating axis of the fan blade and is perpendicular to a plane where the air outlet is located, has a better effect in effect in reducing noise.
- Moreover, the porous member is able to reduce the turbulence occurring when the air current hitting the sharp part between the shorter side plate and the first wall section so as to reduce the noise caused by the turbulence. In addition, the pores of the porous member help the air current to flow into the muffling part and also help to reduce the blade passing frequency noise.
- Furthermore, since the muffling part is made of hard material, the reflected wave is ensured to have the same amplitude as the incident wave so as to completely eliminate the incident wave, thereby increasing the effect in reducing noise.
- Furthermore, the smooth junction between the guiding part and the connecting portion helps the air current generated by the fan blade to flow into the airflow channel.
- In some other embodiment, the muffling part may be made of soft material, such that the muffling part is able to be deformed to change its shape, helping the airflow generator to fit in a laptop computer which has an irregular space.
- Also, the muffling part can be detached from the casing, thus it is more convenient to clean dust therefrom. On the other hand, when the fan blade is replaced by a new fan blade, the muffling part is able to be replaced by another muffling part having an airflow channel having a length equal to one fourth of the wavelength of the blade passing frequency of the new fan blade, thereby maintaining the effect of the noise reduction.
- The embodiments were chosen and described in order to best explain the principles of the disclosure and its practical applications, to thereby enable others skilled in the art to best utilize the disclosure and various embodiments with various modifications as are suited to the particular use contemplated. It is intended that the scope of the disclosure be defined by the following claims and their equivalents.
Claims (11)
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CN201810249200.9 | 2018-03-22 | ||
CN201810249200.9A CN108506231B (en) | 2018-03-22 | 2018-03-22 | Fan device |
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US20190293090A1 true US20190293090A1 (en) | 2019-09-26 |
Family
ID=63378300
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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US16/158,138 Abandoned US20190293090A1 (en) | 2018-03-22 | 2018-10-11 | Airflow generator |
Country Status (2)
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US (1) | US20190293090A1 (en) |
CN (1) | CN108506231B (en) |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
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CN111853966A (en) * | 2019-04-30 | 2020-10-30 | 青岛海尔智能技术研发有限公司 | Noise reduction device and outdoor unit |
Family Cites Families (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2225398A (en) * | 1939-09-13 | 1940-12-17 | Clyde M Hamblin | Construction of ventilating fans |
EP0050621A1 (en) * | 1980-04-28 | 1982-05-05 | KOOPMANN, Gary H. | Noise reduction system |
JPS61192899A (en) * | 1985-02-20 | 1986-08-27 | Matsushita Refrig Co | Centrifugal blower |
JPH07332284A (en) * | 1994-06-13 | 1995-12-22 | Toshiba Corp | Multiblade blower |
JPH1193670A (en) * | 1997-09-19 | 1999-04-06 | Hitachi Constr Mach Co Ltd | Fan shroud |
CN1715681A (en) * | 2004-06-28 | 2006-01-04 | 广达电脑股份有限公司 | Centrifugal fan with resonant silencer |
JP4951916B2 (en) * | 2005-09-29 | 2012-06-13 | パナソニック株式会社 | Blower |
DE102011005025A1 (en) * | 2011-03-03 | 2012-09-06 | Siemens Aktiengesellschaft | Resonator silencer for a radial flow machine, in particular for a centrifugal compressor |
CN205618436U (en) * | 2016-04-27 | 2016-10-05 | 徐工集团工程机械有限公司 | Centrifugal fan and vehicle |
CN108087340A (en) * | 2016-11-21 | 2018-05-29 | 英业达科技有限公司 | Centrifugal fan structure |
-
2018
- 2018-03-22 CN CN201810249200.9A patent/CN108506231B/en active Active
- 2018-10-11 US US16/158,138 patent/US20190293090A1/en not_active Abandoned
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CN108506231A (en) | 2018-09-07 |
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