散热风扇的介绍VIP免费

風扇的性能與應用StevenLin林適之簡介與基本結構基本結構•外框(frame)•馬達(hub)(無刷直流)•扇葉(impeller)•引出線/連接器簡介：風扇是一種產生風量的裝置,它是使用馬達來驅動葉片的轉動,增加流體經過扇葉的速度,經由強制對流達成移熱之效果.BallBearing風扇爆炸圖•1、扣簧•2,5、軸承(ball)•3、外框•4、定子(PCB，矽鋼片+繞線，引出線)•6、彈簧•7、馬達殼+磁條•8、扇葉常見軸風扇尺寸-DeltaAFB25x25x10mm30x30x10mm35x35x10mm40x40x15mm45x45x10mm50x50x15mm50x50x20mm60x60x13mm60x60x15mm60x60x20mm60x60x25.4mm60x60x38mm70x70x13mm70x70x15mm70x70x20mm70x70x25.4mm70x70x38mm80x80x15mm80x80x20mm80x80x25.4mm92x92x15mm92x92x20mm92x92x25.4mm92x92x38mm120x120x25.4mm120x120x38mm172x150x25.4mmφ172x25.4風扇的分類-DCAxialFan軸流扇-airflowsaxially.CentrifugalFan(Blower)離心扇(鼓風扇)-airflowsradially.CrossFan橫流扇-airflowsacrosstheaxis.輸出與控制•輸出–PQ-curve–Noise/Heat–Vibration•控制–FG/RD–PWM/Thermistor→外框、扇葉流体特性•風扇性能曲線PQ-curve–風量(CFM,M3/min)–風壓(mmH2O,inH2O)•噪音(dBa)風切聲：–空氣與扇葉(外框)摩擦產生–氣流擾動產生的噪音轂部(Hub)→電氣特性直流無刷馬達•電氣特性–電流、訊號輸出(RD,FG)、絕緣、反向保護、溫升•轉速控制–運轉電壓：12V→全速運轉；7V→低速運轉–溫控(thermistor)：轉速自動隨環溫變化–PWM((pulse-widemodulation)：增加一組輸入電壓以控制轉速•噪音：電磁切換噪音、摩擦異音定子組立-4極(2極)單面印刷PCB電晶体矽鋼片驅動IC徑向繞線絕緣線架矽鋼片小邊大邊Bearingsystem→LifevsCost•TwoBallBearing–50000/70000hrs/NT16•OneBallOneSleeve–40000hrs/NT10•OneSleeve–30000hrs/NT3•Fluiddynamic(NB-fan)–40000hrs•Lifeisonder4015~65%RHcontinueoperation℃•Costestimateby830ballandsleevebearing•MTTF&AcceleratedLifeTesting–at750/72/300/600/1000hrs90%confidence℃一般twoball結構FGS軸承結構thrustwashersealoilflowcirculationmagneticforce止推墊圈油脂循環流動油封磁力軸套皕瑞-oneball/onesleeve結構PWMorThermistorFromAVCwebsitePWMandThermistorFromAVCwebsite決定成本的重要因素•軸承:30%↑–830(8),520(11.5),620(?),sleeve(3)•830:8→外徑;3→軸心徑•電子零件:30%↑-額定電壓/電流–DriverIC/Hallelement(5~10/2.5)–電晶体、二極体、電阻、電容(0.8~0.1)–引出線&連接器(1~3)•其它–…軸心、矽鋼片、漆包線、葉片、外框風洞示意圖TestpointofPQ-curvePmax,Q=0P=0,QmaxP1+1/2ρV12=P2+1/2ρV22SystemImpedanceandOperatingPointHighImpedanceQQPModerateImpedanceLowImpedanceHighImpedanceLowImpedanceHighPFanHighQFanP輸出比較-相同尺寸Q/Noise與rpm約成正比rpmdBadBa/rpmCFMCFM/rpm280026.50.00946423.380.00835330031.00.00939428.180.00854380034.50.00907933.200.00874430038.50.00895337.540.00873520044.00.00846245.450.00874DELTAAFB0712(7015)轉速愈高，風切聲佔噪音的比重愈高P與rpm的平方約成正比rpmrpm^2mmH2OmmH2O/rpm^2280078400002.272.89541E-073300108900003.122.86501E-073800144400004.122.85319E-074300184900005.332.88264E-075200270400007.792.88092E-07DELTAAFB0712(7015)輸出比較-不同尺寸•相同PQ，風扇尺寸愈大Noise愈小–AFB7025(3900rpm)(q,p,n)=(36.30,5.52,37.5)–AFB8025(3250rpm)(q,p,n)=(37.43,4.59,28.0)•相同厚度，邊(徑)長愈長則Q愈大–AFB7025(3000rpm)(p,q)=(3.15,20.13)–AFB8025(2700rpm)(p,q)=(3.28,31.43)•相同邊(徑)長，厚度愈厚則P愈大–AFB7015(2800rpm)(p,q)=(2.27,23.38)–AFB7025(3600rpm)(p,q)=(4.46,24.01)Delta8015AFBvsEFBAFBEFBDelta8015AFBvsEFB相同P或Q時，EFB>AFBFansinParallelvs.FansinSerial*理想上P&Q會依風扇的數目成倍數成長。*實際上，並聯與理想較接近，較常使用，如1U。*串聯則因為流場與第二顆風扇形成阻抗，損失較多很少使用。*PSU-FAN與CPU-FAN也是一種串...