第5章+真空获得-机械真空泵.ppt
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1、Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and TechnologyVacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology真空物理与技术真空物理与技术第5章真空获得(机械真空泵)Vacuum Science and Technology Vacu
2、um Science and Technology Vacuum Science and Technology Vacuum Science and TechnologyVacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology第第5章章 真空获得真空获得l真空泵概述l机械式真空泵u旋片泵分子泵罗茨泵l气流泵u扩散泵l俘获泵u吸附泵低温泵升华泵离子泵Vacuum Science and Technology Vacu
3、um Science and Technology Vacuum Science and Technology Vacuum Science and TechnologyVacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology真空泵概述真空泵概述Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technol
4、ogy Vacuum Science and TechnologyVacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology什么是真空泵?什么是真空泵?lThis is not a trivial question!u能能对空空间排气(减少气相分子数排气(减少气相分子数,产生低生低压空空间)的)的设备n通通过容容积压缩排气排气(Bulk action)l机械机械压缩n动量量传输(molecular action)l分
5、子直接碰撞分子直接碰撞l夹带:和其他分子碰撞:和其他分子碰撞n降低空降低空间气体分子气体分子浓度度:气体分子气体分子储存在表面存在表面时间 实验时间n所有的真空所有的真空泵都有一定的工作范都有一定的工作范围:l压强l气体种气体种类Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and TechnologyVacuum Science and Technology Vacuum Science and Technology Vacuum
6、 Science and Technology Vacuum Science and Technology抽气原理抽气原理l降低空降低空间气体分子气体分子浓度(度(钛泵、低温、低温泵)l排出气体:旋片排出气体:旋片泵l定向运定向运动:扩散散泵、分子、分子泵、罗茨茨泵l“气体二极管气体二极管”u前前进 反向反向 压力差力差u返流返流(back through-put)反反扩散、脱附散、脱附l真空泵:能够维持压力差的设备Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology
7、Vacuum Science and TechnologyVacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology按照抽气方式分类按照抽气方式分类l压缩性真空泵:将气体由一方压缩到另一方u利用膨胀-压缩-排出原理:旋片泵u利用气体束流牵引作用:蒸汽流喷射泵u利用高速表面牵引分子作用:分子泵l吸附型真空泵:利用各种吸附作用将气体吸掉u利用电离吸气作用:离子泵u利用物理、化学吸附作用:吸附泵、低温泵、吸附剂泵Vacuu
8、m Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and TechnologyVacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology按照压强范围分类按照压强范围分类l粗真空泵粗真空泵:u大气压大气压-10-3 torrn旋片泵旋片泵n旋转柱塞泵旋转柱塞泵n滑片泵滑片
9、泵n吸附泵吸附泵n罗茨泵罗茨泵l高真空泵高真空泵u10-3 to 10-n torrn扩散泵扩散泵n低温泵低温泵n分子泵分子泵n离子泵离子泵Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and TechnologyVacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Te
10、chnology按照排气压强分类按照排气压强分类l排气压强:泵在此压强下可以排气u往大气排气的泵n前级泵n前级压强n旋片式机械泵u只往低于大气压的环境排气n系统粗抽n需要前级泵(串联)n扩散泵、分子泵、罗茨泵u束缚泵n不需要出气口Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and TechnologyVacuum Science and Technology Vacuum Science and Technology Vacuum
11、 Science and Technology Vacuum Science and Technology典型泵组典型泵组粗抽:机械泵主泵:扩散泵前级:机械泵Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and TechnologyVacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Scien
12、ce and Technology真空泵性能的基本参数真空泵性能的基本参数l抽气速率S(抽速)u单位时间流入泵内的气体量Q=S.PS=Q/Pl极限压强puu经过足够长时间的抽气后,所能达到的最低平衡压强l最大工作压强u泵能正常工作的最高压强l使用范围u具有抽气能力的压强范围l排气压强u这一压强下,泵可以可以工作排气l超高真空泵参数u抽气选择性、残余气体组分Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and TechnologyVa
13、cuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology抽速曲线抽速曲线工作压强范围抽速极限压强抽速与气体种类的关系抽速S一般不是常数,随压强变化而变化Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and TechnologyVacuum Science a
14、nd Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology抽速范围抽速范围1.单级旋片泵(无气镇)2.单级气镇泵 3.罗茨泵4.喷射泵 5.扩散泵 6.分子泵Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and TechnologyVacuum Science and Technolog
15、y Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology真空泵的压强范围真空泵的压强范围Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and TechnologyVacuum Science and Technology Vacuum Science and Technology Vacuum Science
16、 and Technology Vacuum Science and Technology抽气曲线抽气曲线l被抽容器中压强随时间变化曲线u不随时间变化的压强就是极限压强u抽速大小由达到一定压强所需时间长短来估计n时间越短,抽速越大Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and TechnologyVacuum Science and Technology Vacuum Science and Technology Vacuum
17、 Science and Technology Vacuum Science and Technology真空系统时间常数真空系统时间常数l问题:S=60L/s的机械泵,对一个体积为10L的容器排气,是否经过10/60s,能将容器抽至P=0呢?u即使是即使是S=常数的理想真空泵,答案也是否定的常数的理想真空泵,答案也是否定的u容器内压强容器内压强P随抽气降低,同一体积(随抽气降低,同一体积(V)对应的气体量()对应的气体量(PV)越来越小越来越小u就气体量而言,抽气实际上越来越慢就气体量而言,抽气实际上越来越慢时间常数越大,压强下降越慢,“惰性”反映系统和泵的综合性能时间常数就是压强值将为1/
18、e所需时间压强降低1个数量级需要2.303个时间常数Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and TechnologyVacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology机械泵机械泵Vacuum Science and Technology
19、Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and TechnologyVacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology早期机械泵早期机械泵l液体泵u利用液体压缩和排气l往复泵斯普伦杰尔泵水喷射泵Vacuum Science and Technology Vacuum Science and Techn
20、ology Vacuum Science and Technology Vacuum Science and TechnologyVacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology水环泵水环泵Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and T
21、echnologyVacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology旋转式真空泵旋转式真空泵l容积压缩泵u使用机械方法使一个工作室体积周期性的扩大和缩小达到抽气目的n旋片式n定片式n滑阀式Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Tec
22、hnologyVacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology旋片泵旋片泵l最常用的粗真空最常用的粗真空泵u皮皮带泵和直和直联泵u单级泵和双和双级泵u实际上就是一个小型旋上就是一个小型旋转压缩机机Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science an
23、d TechnologyVacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology旋片泵工作图旋片泵工作图Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and TechnologyVacuum Science and Technology Vacuum S
24、cience and Technology Vacuum Science and Technology Vacuum Science and Technology最大抽速最大抽速l几何抽速L:泵腔深度(摩擦力)L=0.5-2.0D1否则电动机功耗太高j:翼片伸缩频率一般j=450转/分D2:不能太小,否则旋片泵的翼片容易断裂或密封不良旋片式旋片式:D2=0.75-0.85D1定片式定片式:D2=0.80-0.90D1滑阀式滑阀式:D2=0.65-0.70D1Vacuum Science and Technology Vacuum Science and Technology Vacuum Sc
25、ience and Technology Vacuum Science and TechnologyVacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology有害空间有害空间l理想抽速l理论上的极限压强u压缩比(排气口压强与进气口压强比)l机械泵油封1.有害空间 2.定子 3.转子 4.旋片Vacuum Science and Technology Vacuum Science and Technology Vacu
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