汽(qi)車(che)要跑得快，就必須要有(you)強勁的(de)動(dong)力。目前汽(qi)車(che)的(de)動(dong)力系統(tong)(tong)(tong)可粗分為自(zi)然進氣(qi)系統(tong)(tong)(tong)及(ji)增(zeng)壓(ya)(ya)(ya)(ya)進氣(qi)系統(tong)(tong)(tong)兩(liang)大(da)類。在(zai)歐洲跑車(che)中，除了(le)寶(bao)(bao)馬汽(qi)車(che)公司依(yi)然堅(jian)持使(shi)用(yong)自(zi)然進氣(qi)發動(dong)機(ji)外，其他各汽(qi)車(che)公司為了(le)提(ti)升車(che)輛的(de)動(dong)力性能(neng)(neng)，紛(fen)紛(fen)采(cai)(cai)用(yong)增(zeng)壓(ya)(ya)(ya)(ya)系統(tong)(tong)(tong)，例如：奔(ben)馳跑車(che)使(shi)用(yong)機(ji)械增(zeng)壓(ya)(ya)(ya)(ya)系統(tong)(tong)(tong)，紳寶(bao)(bao)汽(qi)車(che)則為渦輪增(zeng)壓(ya)(ya)(ya)(ya)的(de)開山鼻(bi)祖。近(jin)年日系汽(qi)車(che)也開始大(da)量采(cai)(cai)用(yong)渦輪增(zeng)壓(ya)(ya)(ya)(ya)技術。自(zi)然進氣(qi)系統(tong)(tong)(tong)沒有(you)安裝任何(he)形式的(de)增(zeng)壓(ya)(ya)(ya)(ya)器(qi)，只(zhi)是(shi)利(li)用(yong)活塞下(xia)行所產生的(de)負壓(ya)(ya)(ya)(ya)來吸進混合氣(qi)。雖然自(zi)然進氣(qi)系統(tong)(tong)(tong)通過可變氣(qi)門正時系統(tong)(tong)(tong)能(neng)(neng)夠得到較大(da)的(de)馬力輸出，但(dan)動(dong)力的(de)提(ti)升很(hen)有(you)限。為了(le)有(you)效增(zeng)加發動(dong)機(ji)的(de)輸出功率(lv)，采(cai)(cai)用(yong)增(zeng)壓(ya)(ya)(ya)(ya)系統(tong)(tong)(tong)可說(shuo)是(shi)最有(you)效的(de)方式。

最常見的發動機(ji)(ji)增壓(ya)(ya)系統有機(ji)(ji)械增壓(ya)(ya)與(yu)廢氣渦(wo)輪增壓(ya)(ya)兩(liang)種。

機(ji)械增壓

發(fa)(fa)動(dong)(dong)(dong)機(ji)(ji)(ji)(ji)以機(ji)(ji)(ji)(ji)械(xie)方式驅動(dong)(dong)(dong)機(ji)(ji)(ji)(ji)械(xie)增(zeng)(zeng)(zeng)壓(ya)(ya)(ya)器進(jin)行增(zeng)(zeng)(zeng)壓(ya)(ya)(ya)，稱為機(ji)(ji)(ji)(ji)械(xie)增(zeng)(zeng)(zeng)壓(ya)(ya)(ya)。當發(fa)(fa)動(dong)(dong)(dong)機(ji)(ji)(ji)(ji)采用機(ji)(ji)(ji)(ji)械(xie)增(zeng)(zeng)(zeng)壓(ya)(ya)(ya)時，通(tong)常由(you)(you)發(fa)(fa)動(dong)(dong)(dong)機(ji)(ji)(ji)(ji)曲軸通(tong)過齒輪驅動(dong)(dong)(dong)增(zeng)(zeng)(zeng)壓(ya)(ya)(ya)器。增(zeng)(zeng)(zeng)壓(ya)(ya)(ya)器一般采用離(li)心(xin)式或羅茨壓(ya)(ya)(ya)氣(qi)機(ji)(ji)(ji)(ji)，個別(bie)的(de)采用螺(luo)桿式壓(ya)(ya)(ya)氣(qi)機(ji)(ji)(ji)(ji)。近年來(lai)，在(zai)國(guo)外(wai)也開始采用新型的(de)機(ji)(ji)(ji)(ji)械(xie)渦旋式增(zeng)(zeng)(zeng)壓(ya)(ya)(ya)器。因為驅動(dong)(dong)(dong)壓(ya)(ya)(ya)氣(qi)機(ji)(ji)(ji)(ji)消耗(hao)了發(fa)(fa)動(dong)(dong)(dong)機(ji)(ji)(ji)(ji)一定的(de)輸出(chu)(chu)功率(lv)，所(suo)(suo)以機(ji)(ji)(ji)(ji)械(xie)增(zeng)(zeng)(zeng)壓(ya)(ya)(ya)發(fa)(fa)動(dong)(dong)(dong)機(ji)(ji)(ji)(ji)的(de)熱效(xiao)(xiao)率(lv)不一定得(de)到改(gai)善，有時反而(er)比非增(zeng)(zeng)(zeng)壓(ya)(ya)(ya)內燃機(ji)(ji)(ji)(ji)還(huan)低些。選擇(ze)增(zeng)(zeng)(zeng)壓(ya)(ya)(ya)壓(ya)(ya)(ya)力(li)(li)時，首先要(yao)保證能達到所(suo)(suo)要(yao)求的(de)平(ping)均有效(xiao)(xiao)壓(ya)(ya)(ya)力(li)(li)，其(qi)次(ci)要(yao)獲得(de)盡(jin)可能低的(de)燃油(you)消耗(hao)率(lv)。擔這兩個要(yao)求對于機(ji)(ji)(ji)(ji)械(xie)增(zeng)(zeng)(zeng)壓(ya)(ya)(ya)來(lai)說常常是(shi)相互矛盾的(de)。如(ru)果追求平(ping)均有效(xiao)(xiao)壓(ya)(ya)(ya)力(li)(li)，則(ze)必然導致機(ji)(ji)(ji)(ji)械(xie)效(xiao)(xiao)率(lv)降低，燃油(you)消耗(hao)率(lv)升(sheng)高。因此，增(zeng)(zeng)(zeng)壓(ya)(ya)(ya)壓(ya)(ya)(ya)力(li)(li)值(zhi)的(de)選取應在(zai)功率(lv)和燃油(you)消耗(hao)率(lv)兩者(zhe)之(zhi)間尋(xun)求最(zui)佳的(de)妥協方案。機(ji)(ji)(ji)(ji)械(xie)增(zeng)(zeng)(zeng)壓(ya)(ya)(ya)系統(tong)目前在(zai)歐(ou)洲車上用得(de)較普(pu)遍。由(you)(you)于機(ji)(ji)(ji)(ji)械(xie)增(zeng)(zeng)(zeng)壓(ya)(ya)(ya)的(de)增(zeng)(zeng)(zeng)壓(ya)(ya)(ya)機(ji)(ji)(ji)(ji)是(shi)在(zai)曲軸的(de)帶動(dong)(dong)(dong)下持(chi)續地(di)運轉，因此不動(dong)(dong)(dong)產生(sheng)像渦輪增(zeng)(zeng)(zeng)壓(ya)(ya)(ya)的(de)渦輪遲(chi)滯(zhi)現象(xiang)。機(ji)(ji)(ji)(ji)械(xie)增(zeng)(zeng)(zeng)壓(ya)(ya)(ya)雖然只能提升(sheng)約10%20%的(de)動(dong)(dong)(dong)力(li)(li)輸出(chu)(chu)，但(dan)平(ping)順連續性是(shi)渦輪增(zeng)(zeng)(zeng)壓(ya)(ya)(ya)發(fa)(fa)動(dong)(dong)(dong)機(ji)(ji)(ji)(ji)所(suo)(suo)不及(ji)的(de)。

廢氣渦輪增壓

利(li)用(yong)(yong)發(fa)動(dong)機(ji)(ji)廢(fei)氣(qi)(qi)(qi)(qi)(qi)能量驅動(dong)渦(wo)(wo)輪(lun)(lun)(lun)增(zeng)(zeng)(zeng)(zeng)壓(ya)(ya)(ya)(ya)器，稱為廢(fei)氣(qi)(qi)(qi)(qi)(qi)渦(wo)(wo)輪(lun)(lun)(lun)增(zeng)(zeng)(zeng)(zeng)壓(ya)(ya)(ya)(ya)（簡(jian)稱渦(wo)(wo)輪(lun)(lun)(lun)增(zeng)(zeng)(zeng)(zeng)壓(ya)(ya)(ya)(ya)），如圖所示是廢(fei)氣(qi)(qi)(qi)(qi)(qi)渦(wo)(wo)輪(lun)(lun)(lun)增(zeng)(zeng)(zeng)(zeng)壓(ya)(ya)(ya)(ya)系統。廢(fei)氣(qi)(qi)(qi)(qi)(qi)渦(wo)(wo)輪(lun)(lun)(lun)增(zeng)(zeng)(zeng)(zeng)壓(ya)(ya)(ya)(ya)的(de)特點是在(zai)渦(wo)(wo)輪(lun)(lun)(lun)增(zeng)(zeng)(zeng)(zeng)壓(ya)(ya)(ya)(ya)器和(he)發(fa)動(dong)機(ji)(ji)之(zhi)間(jian)沒有機(ji)(ji)械連接。它們(men)之(zhi)間(jian)靠氣(qi)(qi)(qi)(qi)(qi)路相(xiang)通。因為壓(ya)(ya)(ya)(ya)氣(qi)(qi)(qi)(qi)(qi)機(ji)(ji)消耗(hao)的(de)功(gong)是渦(wo)(wo)輪(lun)(lun)(lun)從廢(fei)氣(qi)(qi)(qi)(qi)(qi)中回收的(de)一部分能量，所以(yi)渦(wo)(wo)輪(lun)(lun)(lun)增(zeng)(zeng)(zeng)(zeng)壓(ya)(ya)(ya)(ya)發(fa)動(dong)機(ji)(ji)不僅可以(yi)增(zeng)(zeng)(zeng)(zeng)加(jia)發(fa)動(dong)機(ji)(ji)的(de)功(gong)率(lv)，而(er)且可以(yi)提高其熱效率(lv)，降(jiang)低燃油(you)消耗(hao)率(lv)。如果在(zai)轎(jiao)車尾部看到Turbo或(huo)者T的(de)標識，即表明該車采用(yong)(yong)的(de)發(fa)動(dong)機(ji)(ji)是渦(wo)(wo)輪(lun)(lun)(lun)增(zeng)(zeng)(zeng)(zeng)壓(ya)(ya)(ya)(ya)的(de)。渦(wo)(wo)輪(lun)(lun)(lun)增(zeng)(zeng)(zeng)(zeng)壓(ya)(ya)(ya)(ya)器實際上是臺(tai)空(kong)(kong)(kong)氣(qi)(qi)(qi)(qi)(qi)壓(ya)(ya)(ya)(ya)縮(suo)(suo)機(ji)(ji)，它是利(li)用(yong)(yong)發(fa)動(dong)機(ji)(ji)排出(chu)的(de)廢(fei)氣(qi)(qi)(qi)(qi)(qi)慣性推動(dong)渦(wo)(wo)輪(lun)(lun)(lun)，渦(wo)(wo)輪(lun)(lun)(lun)又帶動(dong)同軸的(de)葉輪(lun)(lun)(lun)壓(ya)(ya)(ya)(ya)縮(suo)(suo)由空(kong)(kong)(kong)氣(qi)(qi)(qi)(qi)(qi)濾(lv)清器管道送(song)來(lai)的(de)空(kong)(kong)(kong)氣(qi)(qi)(qi)(qi)(qi)，使空(kong)(kong)(kong)氣(qi)(qi)(qi)(qi)(qi)增(zeng)(zeng)(zeng)(zeng)壓(ya)(ya)(ya)(ya)后進(jin)(jin)入氣(qi)(qi)(qi)(qi)(qi)缸。當發(fa)動(dong)機(ji)(ji)轉(zhuan)速提高，廢(fei)氣(qi)(qi)(qi)(qi)(qi)排出(chu)速度(du)與渦(wo)(wo)輪(lun)(lun)(lun)轉(zhuan)速也同步提高，葉輪(lun)(lun)(lun)就(jiu)(jiu)壓(ya)(ya)(ya)(ya)縮(suo)(suo)更多的(de)空(kong)(kong)(kong)氣(qi)(qi)(qi)(qi)(qi)進(jin)(jin)入氣(qi)(qi)(qi)(qi)(qi)缸，空(kong)(kong)(kong)氣(qi)(qi)(qi)(qi)(qi)的(de)壓(ya)(ya)(ya)(ya)力和(he)密度(du)增(zeng)(zeng)(zeng)(zeng)大(da)可以(yi)燃燒更多的(de)燃油(you)，相(xiang)應增(zeng)(zeng)(zeng)(zeng)加(jia)油(you)量和(he)調整一下(xia)發(fa)動(dong)機(ji)(ji)的(de)轉(zhuan)速，就(jiu)(jiu)可以(yi)增(zeng)(zeng)(zeng)(zeng)加(jia)發(fa)動(dong)機(ji)(ji)的(de)輸出(chu)功(gong)率(lv)。