1 简介

真空(kong)泵(beng)是一种旋转式(shi)变容真空(kong)泵(beng)须(xu)有前级泵(beng)配合方可使(shi)用在(zai)较宽的压力(li)范(fan)围内有较大的抽速(su)对被抽除气体中含有灰尘和水蒸汽不(bu)敏感广泛用于冶金(jin)、化工、食品、电子镀膜等行(xing)业。[1]

2 特点

(1)在较宽的(de)压力范围内有较大的(de)抽速；

(2)转(zhuan)(zhuan)(zhuan)(zhuan)子具有(you)良好的几何对(dui)称(cheng)性，故(gu)振动(dong)小，运转(zhuan)(zhuan)(zhuan)(zhuan)平稳。转(zhuan)(zhuan)(zhuan)(zhuan)子间及(ji)转(zhuan)(zhuan)(zhuan)(zhuan)子和壳体间均(jun)有(you)间隙(xi)，不用润(run)滑，摩擦损失小，可大大降低驱动(dong)功率，从(cong)而可实现较高(gao)转(zhuan)(zhuan)(zhuan)(zhuan)速；

(3)泵腔内(nei)无需用油(you)密封和(he)润滑，可减少油(you)蒸气对真(zhen)空系统的污染；

(4)泵腔内无(wu)压缩，无(wu)排气阀。结构简单、紧凑，对被抽气体中(zhong)的(de)灰尘和水蒸汽不敏感；

(5)压缩比较低，对氢气抽气效(xiao)果差；

(6)转子表面为形状较为复杂的曲(qu)线柱面，加(jia)工和检查比较困难(nan)。

3 结构

（1） 泵总体结构(gou)型式(shi)

真空泵(beng)(beng)的(de)泵(beng)(beng)体的(de)布置结(jie)(jie)构决定了泵(beng)(beng)的(de)总(zong)体结(jie)(jie)构。

立(li)式结构的进、排气口(kou)水平设置，装(zhuang)配(pei)和连接管路都比较方便(bian)。但(dan)泵(beng)的重心较高(gao)，在(zai)高(gao)速运转时稳(wen)定性差，故这种型式多用于小泵(beng)。

卧式泵的进气口(kou)在(zai)上，排(pai)(pai)(pai)(pai)气口(kou)在(zai)下(xia)。有时为(wei)了真空系统管(guan)道安装连接(jie)方(fang)(fang)便，可将排(pai)(pai)(pai)(pai)气口(kou)从(cong)水平方(fang)(fang)向接(jie)出(chu)，即进、排(pai)(pai)(pai)(pai)气方(fang)(fang)向是相互垂直(zhi)的。此(ci)时，排(pai)(pai)(pai)(pai)气口(kou)可以从(cong)左或(huo)(huo)右两(liang)个方(fang)(fang)向开口(kou)，除接(jie)排(pai)(pai)(pai)(pai)气管(guan)道一(yi)(yi)端外，另一(yi)(yi)端堵死或(huo)(huo)接(jie)旁(pang)通阀(fa)。这种(zhong)泵结构(gou)重心(xin)低，高速运转时稳定性好。一(yi)(yi)般大、中型泵多采用此(ci)种(zhong)结构(gou)。

泵的两个(ge)转(zhuan)子轴与水平面垂(chui)直安(an)装(zhuang)。这种结构装(zhuang)配间隙容易控制(zhi)，转(zhuan)子装(zhuang)配方(fang)便，泵占(zhan)地面积小。但泵重心(xin)较高(gao)且齿轮拆(chai)装(zhuang)不便，润滑机构也相对复杂。

（2） 泵的(de)传(chuan)动方式

真(zhen)空泵(beng)(beng)的(de)(de)(de)两个(ge)(ge)转(zhuan)子(zi)是通过(guo)(guo)一(yi)(yi)对高精度齿轮(lun)来实现其相对同步运(yun)转(zhuan)的(de)(de)(de)。主动(dong)(dong)(dong)(dong)(dong)(dong)轴(zhou)通过(guo)(guo)联(lian)轴(zhou)器与(yu)电(dian)(dian)机联(lian)接。在传(chuan)动(dong)(dong)(dong)(dong)(dong)(dong)结构(gou)布置上(shang)主要有(you)(you)以(yi)下两种：其一(yi)(yi)是电(dian)(dian)动(dong)(dong)(dong)(dong)(dong)(dong)机与(yu)齿轮(lun)放在转(zhuan)子(zi)的(de)(de)(de)同一(yi)(yi)侧如(ru)图。从动(dong)(dong)(dong)(dong)(dong)(dong)转(zhuan)子(zi)由电(dian)(dian)动(dong)(dong)(dong)(dong)(dong)(dong)机端齿轮(lun)直接传(chuan)过(guo)(guo)去带动(dong)(dong)(dong)(dong)(dong)(dong)，这样主动(dong)(dong)(dong)(dong)(dong)(dong)转(zhuan)子(zi)轴(zhou)的(de)(de)(de)扭(niu)(niu)转(zhuan)变形(xing)小(xiao)，则两个(ge)(ge)转(zhuan)子(zi)之(zhi)间的(de)(de)(de)间隙不(bu)(bu)会因主动(dong)(dong)(dong)(dong)(dong)(dong)轴(zhou)的(de)(de)(de)扭(niu)(niu)转(zhuan)变形(xing)大(da)而改变，故(gu)使转(zhuan)子(zi)之(zhi)间的(de)(de)(de)间隙在运(yun)转(zhuan)过(guo)(guo)程(cheng)中均匀(yun)。这种传(chuan)动(dong)(dong)(dong)(dong)(dong)(dong)方式的(de)(de)(de)最(zui)大(da)缺点(dian)是：a.主动(dong)(dong)(dong)(dong)(dong)(dong)轴(zhou)上(shang)有(you)(you)三个(ge)(ge)轴(zhou)承，增加了泵(beng)(beng)的(de)(de)(de)加工和装配(pei)难度，齿轮(lun)的(de)(de)(de)拆装及调整也不(bu)(bu)便；b.整体结构(gou)不(bu)(bu)匀(yun)称，泵(beng)(beng)的(de)(de)(de)重心偏(pian)向电(dian)(dian)动(dong)(dong)(dong)(dong)(dong)(dong)机和齿轮(lun)箱一(yi)(yi)侧。

    极限(xian)真(zhen)(zhen)(zhen)(zhen)空(kong)(kong)(kong)(kong)(kong)(kong)(kong)”是真(zhen)(zhen)(zhen)(zhen)空(kong)(kong)(kong)(kong)(kong)(kong)(kong)泵的一(yi)个重要参数(shu)，是反应泵抽(chou)气能力(li)的特性值(zhi)，是与(yu)真(zhen)(zhen)(zhen)(zhen)空(kong)(kong)(kong)(kong)(kong)(kong)(kong)泵相关的一(yi)个数(shu)值(zhi)，不同的真(zhen)(zhen)(zhen)(zhen)空(kong)(kong)(kong)(kong)(kong)(kong)(kong)泵可以有不同的“极限(xian)真(zhen)(zhen)(zhen)(zhen)空(kong)(kong)(kong)(kong)(kong)(kong)(kong)”度。而(er)“理论(lun)真(zhen)(zhen)(zhen)(zhen)空(kong)(kong)(kong)(kong)(kong)(kong)(kong)”是理论(lun)研究时(shi)的一(yi)个概念(nian)，是排除各种实际因素的影(ying)响而(er)提炼出的一(yi)种最理想的真(zhen)(zhen)(zhen)(zhen)空(kong)(kong)(kong)(kong)(kong)(kong)(kong)状(zhuang)态(tai)。真(zhen)(zhen)(zhen)(zhen)空(kong)(kong)(kong)(kong)(kong)(kong)(kong)容器(qi)(qi)经(jing)充分(fen)抽(chou)气后，稳定在某一(yi)真(zhen)(zhen)(zhen)(zhen)空(kong)(kong)(kong)(kong)(kong)(kong)(kong)度，此(ci)真(zhen)(zhen)(zhen)(zhen)空(kong)(kong)(kong)(kong)(kong)(kong)(kong)度称为(wei)极限(xian)真(zhen)(zhen)(zhen)(zhen)空(kong)(kong)(kong)(kong)(kong)(kong)(kong)。通(tong)常真(zhen)(zhen)(zhen)(zhen)空(kong)(kong)(kong)(kong)(kong)(kong)(kong)容器(qi)(qi)须经(jing)12小(xiao)(xiao)时(shi)炼气，再经(jing)12小(xiao)(xiao)时(shi)抽(chou)真(zhen)(zhen)(zhen)(zhen)空(kong)(kong)(kong)(kong)(kong)(kong)(kong)，最后一(yi)个小(xiao)(xiao)时(shi)每隔(ge)10分(fen)钟测量一(yi)次(ci)，取其10次(ci)的平(ping)均值(zhi)为(wei)极限(xian)真(zhen)(zhen)(zhen)(zhen)空(kong)(kong)(kong)(kong)(kong)(kong)(kong)值(zhi)。