在(zai)應用羅(luo)茨真空泵(beng)的(de)全過程(cheng)中,大(da)多數羅(luo)茨真空泵(beng)在(zai)常壓下(xia)(xia)無法(fa)直接啟動。為什么(me)呢?我接下(xia)(xia)來向大(da)家(jia)說明理由(you)。
羅茨(ci)真(zhen)(zhen)空(kong)(kong)(kong)(kong)泵(beng)可(ke)以(yi)(yi)包(bao)括低真(zhen)(zhen)空(kong)(kong)(kong)(kong)用的直(zhi)接(jie)排(pai)(pai)(pai)氣常壓(ya)羅茨(ci)真(zhen)(zhen)空(kong)(kong)(kong)(kong)泵(beng)、中高(gao)真(zhen)(zhen)空(kong)(kong)(kong)(kong)用的機械(xie)加壓(ya)泵(beng)、多(duo)級(ji)(ji)羅茨(ci)真(zhen)(zhen)空(kong)(kong)(kong)(kong)泵(beng)。直(zhi)排(pai)(pai)(pai)大氣根真(zhen)(zhen)空(kong)(kong)(kong)(kong)泵(beng)主要是濕根真(zhen)(zhen)空(kong)(kong)(kong)(kong)泵(beng)和風冷(leng)根真(zhen)(zhen)空(kong)(kong)(kong)(kong)泵(beng)(多(duo)級(ji)(ji)根真(zhen)(zhen)空(kong)(kong)(kong)(kong)泵(beng)也(ye)可(ke)以(yi)(yi)直(zhi)接(jie)排(pai)(pai)(pai)風)。直(zhi)排(pai)(pai)(pai)大氣型通道真(zhen)(zhen)空(kong)(kong)(kong)(kong)泵(beng)為了(le)實現常壓(ya)下(xia)的啟(qi)動(dong),采(cai)用結構上犧(xi)牲真(zhen)(zhen)空(kong)(kong)(kong)(kong)度、增大轉子(zi)間隙、改變轉子(zi)結構、強化冷(leng)卻等方式實現高(gao)壓(ya)差下(xia)的運(yun)(yun)行(多(duo)級(ji)(ji)通道泵(beng)采(cai)用多(duo)級(ji)(ji)轉子(zi)串聯實現高(gao)壓(ya)差運(yun)(yun)行)。很多(duo)根源真(zhen)(zhen)空(kong)(kong)(kong)(kong)泵(beng)在常壓(ya)下(xia)無法(fa)直(zhi)接(jie)啟(qi)動(dong)。
一(yi)般的羅茨真空(kong)(kong)泵(beng)(機械加(jia)壓(ya)泵(beng)),為了確保真空(kong)(kong)度和排氣效率,沒有采用上述變化。如果直接排出大(da)氣,則吸(xi)引(yin)口與吸(xi)引(yin)口的壓(ya)差過大(da),吸(xi)引(yin)真空(kong)(kong)泵(beng)過載,無法動作。此(ci)時,若(ruo)增大(da)羅茨真空(kong)(kong)泵(beng)馬達的電力,則熱(re)量增加(jia),羅茨真空(kong)(kong)泵(beng)轉子(zi)過熱(re)而無法散熱(re),殼體的散熱(re)快,之(zhi)間(jian)產生高溫差,羅茨真空(kong)(kong)泵(beng)轉子(zi)的熱(re)膨脹加(jia)速,它們(men)之(zhi)間(jian)和泵(beng)室之(zhi)間(jian)的間(jian)隙消失(shi)而固定。
因(yin)此(ci),為了(le)使(shi)羅(luo)茨真空泵(beng)(beng)(beng)達到高真空度(du),必須確保羅(luo)茨真空泵(beng)(beng)(beng)的轉子(zi)和泵(beng)(beng)(beng)室之(zhi)間的間隙。因(yin)此(ci),大(da)部分中(zhong)高真空泵(beng)(beng)(beng)應配備前置泵(beng)(beng)(beng),將(jiang)系統中(zhong)的壓力(li)引出一定(ding)范圍,然(ran)后啟(qi)動真空泵(beng)(beng)(beng),保證(zheng)進出口(kou)壓差(cha)在合(he)理范圍內,避(bi)免壓差(cha)過(guo)高真空泵(beng)(beng)(beng)過(guo)載。真空泵(beng)(beng)(beng)的前段泵(beng)(beng)(beng),除了(le)水環真空泵(beng)(beng)(beng)、油(you)(you)封式真空泵(beng)(beng)(beng)、往復(fu)式真空泵(beng)(beng)(beng)等可以直接排出大(da)氣的真空泵(beng)(beng)(beng)之(zhi)外(wai),與(yu)無(wu)油(you)(you)真空泵(beng)(beng)(beng)相結合(he),可以選擇大(da)范圍、大(da)吸引速(su)度(du)的無(wu)油(you)(you)真空系統。