CN203384102U - Small axial flow fan with non-uniformly distributed blades - Google Patents
Small axial flow fan with non-uniformly distributed blades Download PDFInfo
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- CN203384102U CN203384102U CN201320395329.3U CN201320395329U CN203384102U CN 203384102 U CN203384102 U CN 203384102U CN 201320395329 U CN201320395329 U CN 201320395329U CN 203384102 U CN203384102 U CN 203384102U
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Abstract
The utility model discloses a small axial flow fan with non-uniformly distributed blades. An existing fan is fine, but the problem of noise radiated by the fan still needs to be solved. The small axial flow fan comprises a casing, the blades, a hub, a motor and a fixing frame, the fixing frame is fixed into the casing, the hub is connected with the motor through a rotating shaft, the motor is fixed on the fixing frame, the blades are circumferentially mounted on the hub by variable pitches, variable pitch distribution of the blades is modulated by the aid of sinusoidal frequency, a sinusoidal frequency modulation formula is phi' i=phi i+A sin(n phi i), the phi i refers to the circumferential angle of the i<th> blade of an equal pitch fan in an impeller, the phi' i refers to the circumferential angle of the i<th> blade of a variable pitch fan in the hub, the A refers to a modulation amplitude, the n refers to the cycle index of modulation, and the circumferential angle of the variable pitch fan varies from -9.75 degrees to 9.75 degrees. The small axial flow fan is economical and environmentally friendly, and the noise is effectively reduced.
Description
Technical field
The utility model belongs to radiation fan noise reduction technology field, relates in particular to a kind of small axial flow fan of blade non-uniform Distribution.
Background technique
Small axial flow fan is easy to use, cost is low, is widely used in civilian and commercial heat dissipation ventilation.In recent years; due to the develop rapidly of computer industry and the raising of people's living standard; high-performance, low noise small axial flow fan become the first-selection of heat radiation; the noise of fan can be divided into discrete and broadband noise from the angle of noise frequency, and the control of noise is generally considered from three angles: the first is set about from the noise reduction sound source; It two is from the propagation of noise way, utilizes silencing apparatus or sound arrester noise reduction; It three is to set about from the noise recipient, and it is protected.The air power noise that fan blade produces is far longer than mechanical noise and the electromagnetic noise of blower fan, if can be by improving fan inlets and putlets of ventilation and blade structure, can reduce significantly the noise of fan radiation, and the noise reduction of trying every possible means from the blade aspect there are very large research and application prospect.So some methods that blade is processed occurred, common are: blade perforation reduce fan eddy current crack, adopt the sweepforward blade to reduce noise, the cutting of plate blade suction surface to reduce noise, adopt softly to go out limit and reduce small flow district noise etc., wherein, adopting not equidistant non-uniform Distribution blade is also a kind of noise reduction measure.What the blade of traditional small axial flow fan adopted is to be uniformly distributed, and the discrete noise peak value that such form fan produces is larger, by changing the distribution form of blade, adopts the irregular pitch non-uniform Distribution can effectively reduce the noise figure of fan.
Summary of the invention
The purpose of this utility model is for the deficiencies in the prior art, a kind of small axial flow fan of blade non-uniform Distribution is provided, by adopting the method for sinusoidal frequency modulation, the distribution form that changes blade is designed a kind of microminiature axial fan of irregular pitch non-uniform Distribution structure, reduces the noise at fan fundamental frequency and harmonic wave place.
The utility model comprises casing, blade, wheel hub, motor, fixing frame, and fixing frame is fixed in casing, and wheel hub is connected with motor by running shaft, and motor is fixed on fixing frame, and blade along circumferentially being arranged on wheel hub irregular pitch.
The irregular pitch of blade distributes and adopts the sinusoidal frequency modulation, and sinusoidal frequency modulation formula is as follows:
Φ'i=Φi+Asin(nΦi)
Wherein, Φ
imean the circumferential angle of i blade of equal pitch fan at impeller, Φ '
imean the circumferential angle of i blade of irregular pitch fan at wheel hub, A is modulated amplitude, and n is the cycle-index of modulation, and the circumferential angle of irregular pitch fan (being non-uniformity) excursion is-9.75 °～9.75 °.
The size of modulated amplitude A has determined the size that the circumferential angle of blade changes, it is the degree of blade uneven distribution, the A value conference reduce the acting ability of fan blade to gas, therefore need consider and guarantee under the influenced little prerequisite of small-sized fans aeroperformance institute this Sine Modulated mode of the employing blade that distributes.In the modulation system that the utility model adopts, research shows, some fans of 7 blades, work as A=5, and during n=1, the circumferential angle excursion of irregular pitch fan is-4.87 °～4.87 °, now the fundamental frequency place noise figure of the fan 1-2dB that descended; Work as A=10, during n=2, the circumferential angle excursion of irregular pitch fan is-9.75 °～9.75 ° now fundamental frequency place noise figure of the fan 1-3dB that descended.These two kinds of modulation systems, the static pressure of fan under design conditions rises all substantially constant.For this fan result of study demonstration of 7 blades, it is a scope preferably that circumferential angle changes-9.75 °～9.75 °, in this restriction range, can select the Leaf positional distribution mode an of the best by the different values of brew cycle frequency n.
The utility model for applicable object be small axial flow fan, adopt the Sine Modulated distribution mode to implement the uneven distribution of blade, the number of blade according to fan self, determine the circumferential angle excursion of each blade by modulated amplitude A, and by change modulates in proper order frequency n specifically be chosen in the circumferential angle of the best of the blade within excursion.
The utility model beneficial effect is as follows:
The utility model is mainly that the mounting type to blade changes, inhomogeneous a week of being distributed in wheel hub by fan blade, after blade irregular pitch non-uniform Distribution, distance between each blade does not wait, broken its periodic regularity, the equal pitch fan unicuspid peak value all occurs at fundamental frequency and harmonic wave place, and less peak value appears in the irregular pitch fan near fundamental frequency place and harmonic wave place and harmonic wave thereof, the irregular pitch fan scatters noise peak neighbouring in wider frequency band, thus the whole noise that has reduced fan.After deliberation, adopt the noise figure integral body of the fan of irregular pitch Leaf positional distribution to descend 1～3 decibel.Adopting irregular pitch blade non-uniform Distribution is a kind of effective small axial flow fan noise reduction measure.
The accompanying drawing explanation
Fig. 1 is the utility model fan scheme of installation;
Fig. 2 is the noise pattern of prototype fan;
Fig. 3 is the noise pattern of the utility model fan;
Fig. 4 means the circumferential angle of i blade of irregular pitch fan at wheel hub in the utility model fan;
In figure, casing 1, blade 2, wheel hub 3, motor 4, fixing frame 5.
Embodiment
Below in conjunction with accompanying drawing, the utility model is described in further detail.
As shown in Figure 1, the small axial flow fan of blade non-uniform Distribution, comprise casing 1, blade 2, wheel hub 3, motor 4, fixing frame 5, fixing frame 5 is fixed in casing 1, wheel hub 3 is connected with motor 4 by running shaft, motor 4 is fixed on fixing frame 5, and blade 2 along circumferentially being arranged on wheel hub 3 irregular pitch.
The irregular pitch of blade 2 distributes and adopts the sinusoidal frequency modulation, and sinusoidal frequency modulation formula is as follows:
Φ’i=Φi+Asin(nΦi)
Wherein, Φ
imean the circumferential angle of i blade of equal pitch fan impeller (being the general designation of blade and wheel hub), Φ '
imean the circumferential angle of i blade of irregular pitch fan at wheel hub 3, specifically can be with reference to Fig. 4, A is modulated amplitude, n is the cycle-index of modulation, and the circumferential angle of irregular pitch fan (being non-uniformity) excursion is-9.75 °～9.75 °.
When circumferentially angle changes in this scope, the fan that the aeroperformance of fan compares to the distribution of blade equal pitch changes little.When the blade equal pitch distributes, rotation blade periodically hits air particle, causes air circle pressure pulsation and produces the crest frequency noise of series of discrete; After blade adopts irregular pitch to distribute, the distance between each blade does not wait, and has broken its periodic regularity; As shown in Figure 2 and Figure 3, the equal pitch fan unicuspid peak value all occurs at fundamental frequency and harmonic wave place, and near the peak value that the irregular pitch fan occurs fundamental frequency place, harmonic wave place and harmonic wave thereof is less than the unicuspid peak value, and near the irregular pitch fan scatters noise peak in wider frequency band, on the whole by the reducing noise of fan 1-3dB.Specifically can be with reference to table 1.
The circumferential angle that table 1 is irregular pitch non-uniform Distribution fan and ricing scope
| ? | Blade 1 | Blade 2 | Blade 3 | Blade 4 | Blade 5 | Blade 6 | Blade 7 |
| Equal pitch | 51.43 | 102.86 | 154.3 | 205.72 | 257.15 | 308.58 | 360 |
| Irregular pitch 1 | 55.34 | 107.73 | 156.47 | 203.55 | 252.58 | 304.67 | 360 |
| Angle changes | 3.91 | 4.87 | 2.17 | -2.17 | -4.87 | -3.91 | 0 |
| Irregular pitch 2 | 61.18 | 98.52 | 146.48 | 213.54 | 261.49 | 298.83 | 360 |
| Angle changes | 9.75 | -4.34 | -7.82 | 7.82 | 4.34 | -9.75 | 0 |
The utility model process is as follows:
Gas axially enters impeller from intake grill, because after the utility model fan blade adopts irregular pitch to distribute, each blade is inconsistent along the circumferential angular distribution of circumference, the periodicity time lag of each blade cuts air-flow is also unequal, therefore the noise component and the frequency that produce are all incomplete same, therefore can avoid the noise stack of identical composition and frequency and the resonance peak that brings.Thereby reduced the blade frequencies noise.
Claims (2)
1. the small axial flow fan of blade non-uniform Distribution, comprise casing, blade, wheel hub, motor, fixing frame, it is characterized in that:
Fixing frame is fixed in casing, and wheel hub is connected with motor by running shaft, and motor is fixed on fixing frame, and blade along circumferentially being arranged on wheel hub irregular pitch;
The irregular pitch of described blade distributes and adopts the sinusoidal frequency modulation, and sinusoidal frequency modulation formula is as follows:
Φ'
i=Φ
i+Asin(nΦ
i)
Wherein, Φ
imean the circumferential angle of i blade of equal pitch fan at impeller, Φ '
imean the circumferential angle of i blade of irregular pitch fan at wheel hub, A is modulated amplitude, and n is the cycle-index of modulation.
2. the small axial flow fan of blade non-uniform Distribution as claimed in claim 1, it is characterized in that: by the different values of brew cycle frequency n, the circumferential angle excursion of irregular pitch fan is-9.75 °～9.75 °.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201320395329.3U CN203384102U (en) | 2013-07-03 | 2013-07-03 | Small axial flow fan with non-uniformly distributed blades |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201320395329.3U CN203384102U (en) | 2013-07-03 | 2013-07-03 | Small axial flow fan with non-uniformly distributed blades |
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| Publication Number | Publication Date |
|---|---|
| CN203384102U true CN203384102U (en) | 2014-01-08 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201320395329.3U Expired - Fee Related CN203384102U (en) | 2013-07-03 | 2013-07-03 | Small axial flow fan with non-uniformly distributed blades |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103438024A (en) * | 2013-07-03 | 2013-12-11 | 浙江理工大学 | Small-sized axial flow fan with blades distributed non-uniformly |
-
2013
- 2013-07-03 CN CN201320395329.3U patent/CN203384102U/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103438024A (en) * | 2013-07-03 | 2013-12-11 | 浙江理工大学 | Small-sized axial flow fan with blades distributed non-uniformly |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20140108 Termination date: 20160703 |
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| CF01 | Termination of patent right due to non-payment of annual fee |