汽車要跑(pao)(pao)得快，就必須要有(you)強勁的動(dong)(dong)力(li)。目前汽車的動(dong)(dong)力(li)系(xi)(xi)(xi)統(tong)(tong)可(ke)粗分為(wei)自然(ran)(ran)進(jin)氣(qi)(qi)系(xi)(xi)(xi)統(tong)(tong)及(ji)增(zeng)(zeng)(zeng)壓(ya)(ya)進(jin)氣(qi)(qi)系(xi)(xi)(xi)統(tong)(tong)兩大類。在(zai)歐洲(zhou)跑(pao)(pao)車中，除了寶(bao)馬(ma)汽車公(gong)司依然(ran)(ran)堅持使(shi)用(yong)自然(ran)(ran)進(jin)氣(qi)(qi)發(fa)(fa)動(dong)(dong)機(ji)外(wai)，其他(ta)各汽車公(gong)司為(wei)了提升車輛的動(dong)(dong)力(li)性能(neng)，紛紛采用(yong)增(zeng)(zeng)(zeng)壓(ya)(ya)系(xi)(xi)(xi)統(tong)(tong)，例如：奔馳跑(pao)(pao)車使(shi)用(yong)機(ji)械增(zeng)(zeng)(zeng)壓(ya)(ya)系(xi)(xi)(xi)統(tong)(tong)，紳寶(bao)汽車則(ze)為(wei)渦輪(lun)增(zeng)(zeng)(zeng)壓(ya)(ya)的開山鼻(bi)祖(zu)。近年日(ri)系(xi)(xi)(xi)汽車也(ye)開始大量采用(yong)渦輪(lun)增(zeng)(zeng)(zeng)壓(ya)(ya)技(ji)術。自然(ran)(ran)進(jin)氣(qi)(qi)系(xi)(xi)(xi)統(tong)(tong)沒有(you)安裝任何形式(shi)的增(zeng)(zeng)(zeng)壓(ya)(ya)器，只是利用(yong)活(huo)塞下行所產生的負(fu)壓(ya)(ya)來吸進(jin)混(hun)合氣(qi)(qi)。雖然(ran)(ran)自然(ran)(ran)進(jin)氣(qi)(qi)系(xi)(xi)(xi)統(tong)(tong)通過可(ke)變氣(qi)(qi)門正(zheng)時系(xi)(xi)(xi)統(tong)(tong)能(neng)夠得到較大的馬(ma)力(li)輸出，但動(dong)(dong)力(li)的提升很(hen)有(you)限(xian)。為(wei)了有(you)效增(zeng)(zeng)(zeng)加發(fa)(fa)動(dong)(dong)機(ji)的輸出功率，采用(yong)增(zeng)(zeng)(zeng)壓(ya)(ya)系(xi)(xi)(xi)統(tong)(tong)可(ke)說(shuo)是最有(you)效的方(fang)式(shi)。

最常見的發動機增壓(ya)系統有(you)機械增壓(ya)與廢氣渦輪增壓(ya)兩種。

機械增(zeng)壓

發(fa)動(dong)(dong)機(ji)(ji)(ji)以機(ji)(ji)(ji)械(xie)方式(shi)驅動(dong)(dong)機(ji)(ji)(ji)械(xie)增(zeng)(zeng)(zeng)壓(ya)(ya)(ya)(ya)(ya)器進行增(zeng)(zeng)(zeng)壓(ya)(ya)(ya)(ya)(ya)，稱為機(ji)(ji)(ji)械(xie)增(zeng)(zeng)(zeng)壓(ya)(ya)(ya)(ya)(ya)。當發(fa)動(dong)(dong)機(ji)(ji)(ji)采(cai)用機(ji)(ji)(ji)械(xie)增(zeng)(zeng)(zeng)壓(ya)(ya)(ya)(ya)(ya)時，通常(chang)由發(fa)動(dong)(dong)機(ji)(ji)(ji)曲軸(zhou)通過齒輪驅動(dong)(dong)增(zeng)(zeng)(zeng)壓(ya)(ya)(ya)(ya)(ya)器。增(zeng)(zeng)(zeng)壓(ya)(ya)(ya)(ya)(ya)器一般采(cai)用離心式(shi)或(huo)羅茨壓(ya)(ya)(ya)(ya)(ya)氣機(ji)(ji)(ji)，個別的(de)(de)(de)(de)采(cai)用螺桿(gan)式(shi)壓(ya)(ya)(ya)(ya)(ya)氣機(ji)(ji)(ji)。近(jin)年來，在(zai)國外(wai)也開(kai)始采(cai)用新型的(de)(de)(de)(de)機(ji)(ji)(ji)械(xie)渦旋式(shi)增(zeng)(zeng)(zeng)壓(ya)(ya)(ya)(ya)(ya)器。因(yin)為驅動(dong)(dong)壓(ya)(ya)(ya)(ya)(ya)氣機(ji)(ji)(ji)消耗(hao)了發(fa)動(dong)(dong)機(ji)(ji)(ji)一定的(de)(de)(de)(de)輸(shu)出功率(lv)(lv)，所以機(ji)(ji)(ji)械(xie)增(zeng)(zeng)(zeng)壓(ya)(ya)(ya)(ya)(ya)發(fa)動(dong)(dong)機(ji)(ji)(ji)的(de)(de)(de)(de)熱效率(lv)(lv)不(bu)一定得到改善，有時反而比非(fei)增(zeng)(zeng)(zeng)壓(ya)(ya)(ya)(ya)(ya)內(nei)燃機(ji)(ji)(ji)還低(di)些。選擇增(zeng)(zeng)(zeng)壓(ya)(ya)(ya)(ya)(ya)壓(ya)(ya)(ya)(ya)(ya)力時，首先要保證能(neng)達到所要求的(de)(de)(de)(de)平(ping)均(jun)有效壓(ya)(ya)(ya)(ya)(ya)力，其次要獲得盡可(ke)能(neng)低(di)的(de)(de)(de)(de)燃油消耗(hao)率(lv)(lv)。擔這兩個要求對(dui)于機(ji)(ji)(ji)械(xie)增(zeng)(zeng)(zeng)壓(ya)(ya)(ya)(ya)(ya)來說常(chang)常(chang)是相互(hu)矛盾的(de)(de)(de)(de)。如果追求平(ping)均(jun)有效壓(ya)(ya)(ya)(ya)(ya)力，則必然導致機(ji)(ji)(ji)械(xie)效率(lv)(lv)降(jiang)低(di)，燃油消耗(hao)率(lv)(lv)升高(gao)。因(yin)此，增(zeng)(zeng)(zeng)壓(ya)(ya)(ya)(ya)(ya)壓(ya)(ya)(ya)(ya)(ya)力值的(de)(de)(de)(de)選取應在(zai)功率(lv)(lv)和燃油消耗(hao)率(lv)(lv)兩者之間尋(xun)求最佳的(de)(de)(de)(de)妥(tuo)協方案。機(ji)(ji)(ji)械(xie)增(zeng)(zeng)(zeng)壓(ya)(ya)(ya)(ya)(ya)系(xi)統(tong)目前在(zai)歐洲車上用得較普(pu)遍。由于機(ji)(ji)(ji)械(xie)增(zeng)(zeng)(zeng)壓(ya)(ya)(ya)(ya)(ya)的(de)(de)(de)(de)增(zeng)(zeng)(zeng)壓(ya)(ya)(ya)(ya)(ya)機(ji)(ji)(ji)是在(zai)曲軸(zhou)的(de)(de)(de)(de)帶(dai)動(dong)(dong)下(xia)持續地運轉，因(yin)此不(bu)動(dong)(dong)產生像渦輪增(zeng)(zeng)(zeng)壓(ya)(ya)(ya)(ya)(ya)的(de)(de)(de)(de)渦輪遲滯現象。機(ji)(ji)(ji)械(xie)增(zeng)(zeng)(zeng)壓(ya)(ya)(ya)(ya)(ya)雖然只(zhi)能(neng)提升約10%20%的(de)(de)(de)(de)動(dong)(dong)力輸(shu)出，但平(ping)順連續性(xing)是渦輪增(zeng)(zeng)(zeng)壓(ya)(ya)(ya)(ya)(ya)發(fa)動(dong)(dong)機(ji)(ji)(ji)所不(bu)及(ji)的(de)(de)(de)(de)。

廢氣渦輪增壓

利用發(fa)(fa)(fa)(fa)動(dong)(dong)(dong)機(ji)(ji)廢(fei)(fei)氣(qi)(qi)(qi)能(neng)量(liang)驅(qu)動(dong)(dong)(dong)渦(wo)(wo)(wo)輪(lun)(lun)(lun)增(zeng)(zeng)(zeng)(zeng)壓(ya)器(qi)，稱為廢(fei)(fei)氣(qi)(qi)(qi)渦(wo)(wo)(wo)輪(lun)(lun)(lun)增(zeng)(zeng)(zeng)(zeng)壓(ya)（簡稱渦(wo)(wo)(wo)輪(lun)(lun)(lun)增(zeng)(zeng)(zeng)(zeng)壓(ya)），如圖所示是(shi)(shi)(shi)廢(fei)(fei)氣(qi)(qi)(qi)渦(wo)(wo)(wo)輪(lun)(lun)(lun)增(zeng)(zeng)(zeng)(zeng)壓(ya)系(xi)統。廢(fei)(fei)氣(qi)(qi)(qi)渦(wo)(wo)(wo)輪(lun)(lun)(lun)增(zeng)(zeng)(zeng)(zeng)壓(ya)的(de)特點是(shi)(shi)(shi)在渦(wo)(wo)(wo)輪(lun)(lun)(lun)增(zeng)(zeng)(zeng)(zeng)壓(ya)器(qi)和發(fa)(fa)(fa)(fa)動(dong)(dong)(dong)機(ji)(ji)之間沒有機(ji)(ji)械連接。它們之間靠(kao)氣(qi)(qi)(qi)路相通(tong)。因為壓(ya)氣(qi)(qi)(qi)機(ji)(ji)消耗的(de)功(gong)是(shi)(shi)(shi)渦(wo)(wo)(wo)輪(lun)(lun)(lun)從廢(fei)(fei)氣(qi)(qi)(qi)中回(hui)收的(de)一部分能(neng)量(liang)，所以(yi)(yi)渦(wo)(wo)(wo)輪(lun)(lun)(lun)增(zeng)(zeng)(zeng)(zeng)壓(ya)發(fa)(fa)(fa)(fa)動(dong)(dong)(dong)機(ji)(ji)不僅(jin)可(ke)以(yi)(yi)增(zeng)(zeng)(zeng)(zeng)加(jia)發(fa)(fa)(fa)(fa)動(dong)(dong)(dong)機(ji)(ji)的(de)功(gong)率，而且可(ke)以(yi)(yi)提高其熱效率，降低燃油(you)消耗率。如果在轎車尾(wei)部看到Turbo或者(zhe)T的(de)標識(shi)，即表明該車采用的(de)發(fa)(fa)(fa)(fa)動(dong)(dong)(dong)機(ji)(ji)是(shi)(shi)(shi)渦(wo)(wo)(wo)輪(lun)(lun)(lun)增(zeng)(zeng)(zeng)(zeng)壓(ya)的(de)。渦(wo)(wo)(wo)輪(lun)(lun)(lun)增(zeng)(zeng)(zeng)(zeng)壓(ya)器(qi)實(shi)際上(shang)是(shi)(shi)(shi)臺空(kong)(kong)氣(qi)(qi)(qi)壓(ya)縮(suo)(suo)機(ji)(ji)，它是(shi)(shi)(shi)利用發(fa)(fa)(fa)(fa)動(dong)(dong)(dong)機(ji)(ji)排(pai)出(chu)的(de)廢(fei)(fei)氣(qi)(qi)(qi)慣性推動(dong)(dong)(dong)渦(wo)(wo)(wo)輪(lun)(lun)(lun)，渦(wo)(wo)(wo)輪(lun)(lun)(lun)又帶動(dong)(dong)(dong)同軸的(de)葉輪(lun)(lun)(lun)壓(ya)縮(suo)(suo)由(you)空(kong)(kong)氣(qi)(qi)(qi)濾(lv)清器(qi)管道送(song)來的(de)空(kong)(kong)氣(qi)(qi)(qi)，使空(kong)(kong)氣(qi)(qi)(qi)增(zeng)(zeng)(zeng)(zeng)壓(ya)后(hou)進入氣(qi)(qi)(qi)缸。當發(fa)(fa)(fa)(fa)動(dong)(dong)(dong)機(ji)(ji)轉速提高，廢(fei)(fei)氣(qi)(qi)(qi)排(pai)出(chu)速度與渦(wo)(wo)(wo)輪(lun)(lun)(lun)轉速也同步(bu)提高，葉輪(lun)(lun)(lun)就壓(ya)縮(suo)(suo)更(geng)多(duo)的(de)空(kong)(kong)氣(qi)(qi)(qi)進入氣(qi)(qi)(qi)缸，空(kong)(kong)氣(qi)(qi)(qi)的(de)壓(ya)力和密度增(zeng)(zeng)(zeng)(zeng)大可(ke)以(yi)(yi)燃燒(shao)更(geng)多(duo)的(de)燃油(you)，相應增(zeng)(zeng)(zeng)(zeng)加(jia)油(you)量(liang)和調整一下發(fa)(fa)(fa)(fa)動(dong)(dong)(dong)機(ji)(ji)的(de)轉速，就可(ke)以(yi)(yi)增(zeng)(zeng)(zeng)(zeng)加(jia)發(fa)(fa)(fa)(fa)動(dong)(dong)(dong)機(ji)(ji)的(de)輸出(chu)功(gong)率。