汽(qi)車(che)(che)要跑(pao)得(de)(de)快，就(jiu)必(bi)須要有(you)強勁的(de)動(dong)(dong)力(li)(li)。目前汽(qi)車(che)(che)的(de)動(dong)(dong)力(li)(li)系(xi)(xi)(xi)統(tong)可(ke)(ke)粗分為(wei)自(zi)然(ran)進(jin)(jin)氣(qi)(qi)系(xi)(xi)(xi)統(tong)及增壓(ya)(ya)進(jin)(jin)氣(qi)(qi)系(xi)(xi)(xi)統(tong)兩(liang)大類。在歐(ou)洲跑(pao)車(che)(che)中，除(chu)了寶馬汽(qi)車(che)(che)公(gong)司依然(ran)堅持使用自(zi)然(ran)進(jin)(jin)氣(qi)(qi)發(fa)動(dong)(dong)機外，其他各汽(qi)車(che)(che)公(gong)司為(wei)了提(ti)升(sheng)車(che)(che)輛的(de)動(dong)(dong)力(li)(li)性能，紛(fen)(fen)紛(fen)(fen)采(cai)用增壓(ya)(ya)系(xi)(xi)(xi)統(tong)，例如：奔馳跑(pao)車(che)(che)使用機械增壓(ya)(ya)系(xi)(xi)(xi)統(tong)，紳寶汽(qi)車(che)(che)則為(wei)渦輪增壓(ya)(ya)的(de)開山鼻(bi)祖(zu)。近年日系(xi)(xi)(xi)汽(qi)車(che)(che)也開始大量采(cai)用渦輪增壓(ya)(ya)技術。自(zi)然(ran)進(jin)(jin)氣(qi)(qi)系(xi)(xi)(xi)統(tong)沒有(you)安(an)裝(zhuang)任何(he)形式的(de)增壓(ya)(ya)器，只(zhi)是(shi)利用活(huo)塞下行所產生的(de)負壓(ya)(ya)來吸進(jin)(jin)混合(he)氣(qi)(qi)。雖然(ran)自(zi)然(ran)進(jin)(jin)氣(qi)(qi)系(xi)(xi)(xi)統(tong)通過可(ke)(ke)變氣(qi)(qi)門正時系(xi)(xi)(xi)統(tong)能夠得(de)(de)到較大的(de)馬力(li)(li)輸出(chu)，但(dan)動(dong)(dong)力(li)(li)的(de)提(ti)升(sheng)很有(you)限。為(wei)了有(you)效增加(jia)發(fa)動(dong)(dong)機的(de)輸出(chu)功率(lv)，采(cai)用增壓(ya)(ya)系(xi)(xi)(xi)統(tong)可(ke)(ke)說(shuo)是(shi)最(zui)有(you)效的(de)方式。

最常(chang)見(jian)的發動機(ji)增壓系(xi)統有(you)機(ji)械增壓與廢氣(qi)渦輪增壓兩種。

機械增壓

發(fa)動(dong)(dong)(dong)機(ji)(ji)(ji)以機(ji)(ji)(ji)械方式(shi)(shi)(shi)驅動(dong)(dong)(dong)機(ji)(ji)(ji)械增(zeng)(zeng)(zeng)壓(ya)(ya)(ya)(ya)器(qi)進行增(zeng)(zeng)(zeng)壓(ya)(ya)(ya)(ya)，稱為機(ji)(ji)(ji)械增(zeng)(zeng)(zeng)壓(ya)(ya)(ya)(ya)。當發(fa)動(dong)(dong)(dong)機(ji)(ji)(ji)采(cai)用(yong)機(ji)(ji)(ji)械增(zeng)(zeng)(zeng)壓(ya)(ya)(ya)(ya)時，通常由發(fa)動(dong)(dong)(dong)機(ji)(ji)(ji)曲軸(zhou)通過齒(chi)輪驅動(dong)(dong)(dong)增(zeng)(zeng)(zeng)壓(ya)(ya)(ya)(ya)器(qi)。增(zeng)(zeng)(zeng)壓(ya)(ya)(ya)(ya)器(qi)一般采(cai)用(yong)離心(xin)式(shi)(shi)(shi)或羅茨(ci)壓(ya)(ya)(ya)(ya)氣機(ji)(ji)(ji)，個別(bie)的(de)采(cai)用(yong)螺桿式(shi)(shi)(shi)壓(ya)(ya)(ya)(ya)氣機(ji)(ji)(ji)。近年來(lai)，在國外也開始采(cai)用(yong)新型的(de)機(ji)(ji)(ji)械渦旋式(shi)(shi)(shi)增(zeng)(zeng)(zeng)壓(ya)(ya)(ya)(ya)器(qi)。因(yin)(yin)為驅動(dong)(dong)(dong)壓(ya)(ya)(ya)(ya)氣機(ji)(ji)(ji)消(xiao)耗了(le)發(fa)動(dong)(dong)(dong)機(ji)(ji)(ji)一定(ding)的(de)輸(shu)出功率(lv)，所(suo)以機(ji)(ji)(ji)械增(zeng)(zeng)(zeng)壓(ya)(ya)(ya)(ya)發(fa)動(dong)(dong)(dong)機(ji)(ji)(ji)的(de)熱效(xiao)率(lv)不一定(ding)得到(dao)改善，有時反而(er)比非(fei)增(zeng)(zeng)(zeng)壓(ya)(ya)(ya)(ya)內燃機(ji)(ji)(ji)還低(di)些。選擇增(zeng)(zeng)(zeng)壓(ya)(ya)(ya)(ya)壓(ya)(ya)(ya)(ya)力(li)時，首先要(yao)保(bao)證能(neng)達(da)到(dao)所(suo)要(yao)求(qiu)的(de)平(ping)(ping)均有效(xiao)壓(ya)(ya)(ya)(ya)力(li)，其次要(yao)獲得盡可能(neng)低(di)的(de)燃油消(xiao)耗率(lv)。擔這兩個要(yao)求(qiu)對于(yu)機(ji)(ji)(ji)械增(zeng)(zeng)(zeng)壓(ya)(ya)(ya)(ya)來(lai)說常常是(shi)相互(hu)矛(mao)盾的(de)。如果追求(qiu)平(ping)(ping)均有效(xiao)壓(ya)(ya)(ya)(ya)力(li)，則(ze)必然導致機(ji)(ji)(ji)械效(xiao)率(lv)降低(di)，燃油消(xiao)耗率(lv)升高。因(yin)(yin)此，增(zeng)(zeng)(zeng)壓(ya)(ya)(ya)(ya)壓(ya)(ya)(ya)(ya)力(li)值的(de)選取應(ying)在功率(lv)和燃油消(xiao)耗率(lv)兩者(zhe)之(zhi)間尋求(qiu)最佳(jia)的(de)妥協方案。機(ji)(ji)(ji)械增(zeng)(zeng)(zeng)壓(ya)(ya)(ya)(ya)系統目(mu)前在歐洲車上(shang)用(yong)得較普遍。由于(yu)機(ji)(ji)(ji)械增(zeng)(zeng)(zeng)壓(ya)(ya)(ya)(ya)的(de)增(zeng)(zeng)(zeng)壓(ya)(ya)(ya)(ya)機(ji)(ji)(ji)是(shi)在曲軸(zhou)的(de)帶動(dong)(dong)(dong)下持續(xu)地運(yun)轉，因(yin)(yin)此不動(dong)(dong)(dong)產生像渦輪增(zeng)(zeng)(zeng)壓(ya)(ya)(ya)(ya)的(de)渦輪遲(chi)滯(zhi)現(xian)象。機(ji)(ji)(ji)械增(zeng)(zeng)(zeng)壓(ya)(ya)(ya)(ya)雖然只能(neng)提升約(yue)10%20%的(de)動(dong)(dong)(dong)力(li)輸(shu)出，但平(ping)(ping)順連(lian)續(xu)性是(shi)渦輪增(zeng)(zeng)(zeng)壓(ya)(ya)(ya)(ya)發(fa)動(dong)(dong)(dong)機(ji)(ji)(ji)所(suo)不及的(de)。

廢(fei)氣渦輪增壓

利用發(fa)(fa)動(dong)(dong)(dong)機(ji)(ji)(ji)廢(fei)氣(qi)能量(liang)驅(qu)動(dong)(dong)(dong)渦(wo)(wo)(wo)(wo)輪(lun)(lun)(lun)增(zeng)(zeng)(zeng)壓(ya)(ya)(ya)器，稱為廢(fei)氣(qi)渦(wo)(wo)(wo)(wo)輪(lun)(lun)(lun)增(zeng)(zeng)(zeng)壓(ya)(ya)(ya)（簡(jian)稱渦(wo)(wo)(wo)(wo)輪(lun)(lun)(lun)增(zeng)(zeng)(zeng)壓(ya)(ya)(ya)），如圖所(suo)示是(shi)廢(fei)氣(qi)渦(wo)(wo)(wo)(wo)輪(lun)(lun)(lun)增(zeng)(zeng)(zeng)壓(ya)(ya)(ya)系統。廢(fei)氣(qi)渦(wo)(wo)(wo)(wo)輪(lun)(lun)(lun)增(zeng)(zeng)(zeng)壓(ya)(ya)(ya)的(de)(de)(de)(de)特點是(shi)在渦(wo)(wo)(wo)(wo)輪(lun)(lun)(lun)增(zeng)(zeng)(zeng)壓(ya)(ya)(ya)器和(he)(he)發(fa)(fa)動(dong)(dong)(dong)機(ji)(ji)(ji)之間(jian)(jian)沒有機(ji)(ji)(ji)械連接。它們之間(jian)(jian)靠氣(qi)路相(xiang)通。因為壓(ya)(ya)(ya)氣(qi)機(ji)(ji)(ji)消耗的(de)(de)(de)(de)功是(shi)渦(wo)(wo)(wo)(wo)輪(lun)(lun)(lun)從廢(fei)氣(qi)中(zhong)回(hui)收的(de)(de)(de)(de)一(yi)部分(fen)能量(liang)，所(suo)以(yi)渦(wo)(wo)(wo)(wo)輪(lun)(lun)(lun)增(zeng)(zeng)(zeng)壓(ya)(ya)(ya)發(fa)(fa)動(dong)(dong)(dong)機(ji)(ji)(ji)不僅可以(yi)增(zeng)(zeng)(zeng)加(jia)發(fa)(fa)動(dong)(dong)(dong)機(ji)(ji)(ji)的(de)(de)(de)(de)功率(lv)，而且可以(yi)提(ti)高其熱(re)效率(lv)，降低(di)燃(ran)油消耗率(lv)。如果(guo)在轎車尾(wei)部看(kan)到Turbo或者T的(de)(de)(de)(de)標識，即表明該車采用的(de)(de)(de)(de)發(fa)(fa)動(dong)(dong)(dong)機(ji)(ji)(ji)是(shi)渦(wo)(wo)(wo)(wo)輪(lun)(lun)(lun)增(zeng)(zeng)(zeng)壓(ya)(ya)(ya)的(de)(de)(de)(de)。渦(wo)(wo)(wo)(wo)輪(lun)(lun)(lun)增(zeng)(zeng)(zeng)壓(ya)(ya)(ya)器實際(ji)上是(shi)臺(tai)空(kong)(kong)(kong)(kong)氣(qi)壓(ya)(ya)(ya)縮(suo)機(ji)(ji)(ji)，它是(shi)利用發(fa)(fa)動(dong)(dong)(dong)機(ji)(ji)(ji)排(pai)出的(de)(de)(de)(de)廢(fei)氣(qi)慣性推動(dong)(dong)(dong)渦(wo)(wo)(wo)(wo)輪(lun)(lun)(lun)，渦(wo)(wo)(wo)(wo)輪(lun)(lun)(lun)又帶(dai)動(dong)(dong)(dong)同(tong)軸的(de)(de)(de)(de)葉(xie)輪(lun)(lun)(lun)壓(ya)(ya)(ya)縮(suo)由空(kong)(kong)(kong)(kong)氣(qi)濾(lv)清器管道送來的(de)(de)(de)(de)空(kong)(kong)(kong)(kong)氣(qi)，使空(kong)(kong)(kong)(kong)氣(qi)增(zeng)(zeng)(zeng)壓(ya)(ya)(ya)后進(jin)入(ru)氣(qi)缸。當發(fa)(fa)動(dong)(dong)(dong)機(ji)(ji)(ji)轉(zhuan)速提(ti)高，廢(fei)氣(qi)排(pai)出速度與(yu)渦(wo)(wo)(wo)(wo)輪(lun)(lun)(lun)轉(zhuan)速也同(tong)步提(ti)高，葉(xie)輪(lun)(lun)(lun)就(jiu)壓(ya)(ya)(ya)縮(suo)更多的(de)(de)(de)(de)空(kong)(kong)(kong)(kong)氣(qi)進(jin)入(ru)氣(qi)缸，空(kong)(kong)(kong)(kong)氣(qi)的(de)(de)(de)(de)壓(ya)(ya)(ya)力和(he)(he)密度增(zeng)(zeng)(zeng)大可以(yi)燃(ran)燒更多的(de)(de)(de)(de)燃(ran)油，相(xiang)應增(zeng)(zeng)(zeng)加(jia)油量(liang)和(he)(he)調整一(yi)下發(fa)(fa)動(dong)(dong)(dong)機(ji)(ji)(ji)的(de)(de)(de)(de)轉(zhuan)速，就(jiu)可以(yi)增(zeng)(zeng)(zeng)加(jia)發(fa)(fa)動(dong)(dong)(dong)機(ji)(ji)(ji)的(de)(de)(de)(de)輸出功率(lv)。