外文翻譯--內(nèi)燃機(jī)

1、<p>　　畢業(yè)設(shè)計(jì)(論文)外文資料翻譯</p><p>　　系　　部： 機(jī)械工程系 </p><p>　　專 業(yè)： 機(jī)械工程及自動(dòng)化 </p><p>　　姓 名： </p>

2、<p>　　學(xué) 號(hào)： </p><p>　　外文出處：http://bbs.jobmet.com/thread-261802-1</p><p>　　-1.html </p><p>　　附 件： 1.外文資料翻譯譯文；2.外文原文。 &

3、lt;/p><p>　　注：請(qǐng)將該封面與附件裝訂成冊(cè)。</p><p>　　附件1：外文資料翻譯譯文</p><p><b>　　內(nèi)燃機(jī)</b></p><p>　　我們知道，無論是汽油發(fā)動(dòng)機(jī)還是柴油發(fā)動(dòng)機(jī)，它們都屬于內(nèi)燃機(jī)，都是燃燒燃料后通過推動(dòng)氣缸內(nèi)活塞作往返運(yùn)動(dòng)來將燃料中的化學(xué)能量轉(zhuǎn)換成為驅(qū)動(dòng)車輛前進(jìn)的機(jī)械能量，因此兩

4、者的工作原理大體是相同的。</p><p>　　作為日常使用的燃料本身，柴油的能量密度最高，比液化天然氣高出近1倍，比汽油高出10%以上。與汽油相比，柴油不易揮發(fā)，著火點(diǎn)較高，不易因偶然情況被點(diǎn)燃或發(fā)生爆炸。由于兩者揮發(fā)性和燃點(diǎn)的不同，導(dǎo)致使用這兩種燃料的發(fā)動(dòng)機(jī)有不同的點(diǎn)火方式。</p><p>　　汽油發(fā)動(dòng)機(jī)的特點(diǎn)：體積小、重量輕、起動(dòng)性好。</p><p>　　

5、汽油發(fā)動(dòng)機(jī)中，油氣混合氣進(jìn)入氣缸后，在壓縮接近終了時(shí)由火花塞點(diǎn)燃。因此，汽油發(fā)動(dòng)機(jī)需要一套控制何時(shí)讓火花塞工作的點(diǎn)火系統(tǒng)，此系統(tǒng)必須精確控制火花塞放電的時(shí)刻和火花能量的大小，才能保證汽油機(jī)的工作正常，汽油機(jī)的燃料供給系和點(diǎn)火系是汽油機(jī)上發(fā)生故障比例較高的部位。此外，由于汽油的燃點(diǎn)較低，汽油機(jī)的壓縮比就不能太高，以免油氣自燃，因此其熱效率和經(jīng)濟(jì)性較柴油機(jī)為差。</p><p>　　汽油機(jī)的優(yōu)點(diǎn)在于其體積小、重量輕、

6、價(jià)格便宜；起動(dòng)性好，最大功率時(shí)的轉(zhuǎn)速高；工作中振動(dòng)及噪聲小，因此，在載客汽車，特別是轎車中，汽油機(jī)得到了廣泛的應(yīng)用，特別是在我們國(guó)家目前生產(chǎn)的絕大多數(shù)轎車，都是采用汽油發(fā)動(dòng)機(jī)作為自己的動(dòng)力系統(tǒng)。</p><p>　　傳統(tǒng)柴油發(fā)動(dòng)機(jī)的特點(diǎn)：熱效率和經(jīng)濟(jì)性較好。</p><p>　　柴油機(jī)采用壓縮空氣的辦法提高空氣溫度，使空氣溫度超過柴油的自燃燃點(diǎn)，這時(shí)再噴入柴油、柴油噴霧和空氣混合的同時(shí)自己

7、點(diǎn)火燃燒。因此，柴油發(fā)動(dòng)機(jī)無需點(diǎn)火系。同時(shí)，柴油機(jī)的供油系統(tǒng)也相對(duì)簡(jiǎn)單，因此柴油發(fā)動(dòng)機(jī)的可靠性要比汽油發(fā)動(dòng)機(jī)的好。</p><p>　　由于不受爆燃的限制以及柴油自燃的需要，柴油機(jī)壓縮比很高。熱效率和經(jīng)濟(jì)性都要好于汽油機(jī)，同時(shí)在相同功率的情況下，柴油機(jī)的扭矩大，最大功率時(shí)的轉(zhuǎn)速低，適合于載貨汽車的使用。</p><p>　　但柴油機(jī)由于工作壓力大，要求各有關(guān)零件具有較高的結(jié)構(gòu)強(qiáng)度和剛度，所

8、以柴油機(jī)比較笨重，體積較大；柴油機(jī)的噴油泵與噴嘴制造精度要求高，所以成本較高；另外，柴油機(jī)工作粗暴，振動(dòng)噪聲大；柴油不易蒸發(fā)，冬季冷車時(shí)起動(dòng)困難。</p><p>　　由于上述特點(diǎn)，以前柴油發(fā)動(dòng)機(jī)一般用于大、中型載重貨車上。</p><p>　　小型高速柴油發(fā)動(dòng)機(jī)的新發(fā)展：排放已經(jīng)達(dá)到歐洲III號(hào)的標(biāo)準(zhǔn)。</p><p>　　傳統(tǒng)上，柴油發(fā)動(dòng)機(jī)由于比較笨重，升功率指

9、標(biāo)不如汽油機(jī)(轉(zhuǎn)速較低)，噪聲、振動(dòng)較高，炭煙與顆粒(PM)排放比較嚴(yán)重，所以一直以來很少受到轎車的青睞。</p><p>　　但隨著近年來柴油機(jī)技術(shù)的進(jìn)步，特別是小型高速柴油發(fā)動(dòng)機(jī)的新發(fā)展，一批先進(jìn)的技術(shù)，例如電控直噴、共軌、渦輪增壓、中冷等技術(shù)得以在小型柴油發(fā)動(dòng)機(jī)上應(yīng)用，使原來柴油發(fā)動(dòng)機(jī)存在的缺點(diǎn)得到了較好的解決，而柴油機(jī)在節(jié)能與CO2排放方面的優(yōu)勢(shì)，則是包括汽油機(jī)在內(nèi)的所有熱力發(fā)動(dòng)機(jī)無法取代的，因此，先進(jìn)的

10、小型高速柴油發(fā)動(dòng)機(jī)，其排放已經(jīng)達(dá)到歐洲III號(hào)的標(biāo)準(zhǔn)，成為“綠色發(fā)動(dòng)機(jī)”，目前已經(jīng)成為歐美許多新轎車的動(dòng)力裝置，可以預(yù)見，我國(guó)將出現(xiàn)越來越多的柴油轎車。</p><p>　　內(nèi)燃機(jī)是一種熱力發(fā)動(dòng)機(jī)。通常可按燃用的燃料來分有：汽油機(jī)、煤氣機(jī)等幾類。因?yàn)槠蜋C(jī)輕便、噪音低以及環(huán)保性，它贏得了公眾較好的口碑，因此其有機(jī)在國(guó)民經(jīng)濟(jì)和國(guó)防工程上得到了較為廣泛的應(yīng)用。內(nèi)燃機(jī)傳熱在很大程度上主宰著汽油機(jī)的經(jīng)濟(jì)性、可靠性以及其他

11、各項(xiàng)重要的技術(shù)經(jīng)濟(jì)指標(biāo)。在汽油機(jī)負(fù)載日益增強(qiáng)的今天，研究汽油機(jī)熱負(fù)荷問題已經(jīng)是非常緊迫的任務(wù)了。汽油機(jī)向高強(qiáng)化方向的發(fā)展使其零部件的機(jī)械負(fù)荷和熱負(fù)荷不斷增大，而汽油機(jī)的的汽缸套是氣體壓縮、燃燒和膨脹的空間，并為活塞起導(dǎo)向作用，它的不正常變形將破壞活塞與缸套間的正常間隙，導(dǎo)致工作過程的惡化。因而，如何降低汽油機(jī)的熱負(fù)荷，則是提高其整機(jī)性能的重要研究課題。 </p><p><b>　　發(fā)動(dòng)機(jī)：</b

12、></p><p>　　發(fā)動(dòng)機(jī)充當(dāng)動(dòng)力裝置。內(nèi)燃機(jī)是最常見的：它通過在發(fā)動(dòng)機(jī)汽缸里面燃燒一種液體燃料獲得動(dòng)力。發(fā)動(dòng)機(jī)有兩種類型:汽油機(jī) (也叫做一個(gè)火花- 點(diǎn)火發(fā)動(dòng)機(jī))和柴油機(jī)(也被稱為一個(gè)壓縮- 點(diǎn)火發(fā)動(dòng)機(jī))。這兩種發(fā)動(dòng)機(jī)都叫做熱機(jī)；燃料在氣缸內(nèi)燃燒產(chǎn)生的高溫高壓氣體推動(dòng)曲軸旋轉(zhuǎn)而傳遞動(dòng)力。</p><p><b>　　車身：</b></p>&

13、lt;p>　　汽車車身是由窗子，門，一個(gè)發(fā)動(dòng)機(jī)罩和一個(gè)行李艙蓋建成的一個(gè)金屬板殼。它給發(fā)動(dòng)機(jī)，乘客和貨物提供一種保護(hù)。車身的設(shè)計(jì)應(yīng)使得乘客安全和舒適。車身的外表使得汽車具有吸引人的，五彩繽紛的和現(xiàn)代的外表。</p><p><b>　　底盤：</b></p><p>　　底盤是汽車上主要操作系統(tǒng)組成的一個(gè)總成。底盤包括傳動(dòng)系，懸掛，轉(zhuǎn)向，以及剎車系統(tǒng)。</

14、p><p>　　傳動(dòng)系統(tǒng) - 把動(dòng)力運(yùn)送到車輪。主要零部件是離合器，變速器，傳動(dòng)軸，主減速器，和差速器。</p><p>　　懸掛 - 吸收路面震動(dòng)。</p><p>　　轉(zhuǎn)向 - 控制運(yùn)動(dòng)的方向。</p><p>　　剎車 – 使車輛減速。</p><p><b>　　電氣設(shè)備：</b></p

15、><p>　　電系統(tǒng)為點(diǎn)火，喇叭，燈光，發(fā)熱器和起動(dòng)器提供電。通過循環(huán)充電來維持電量。這條電路由電池，交流發(fā)電機(jī)(或者發(fā)電機(jī))組成。蓄電池儲(chǔ)存電。交流發(fā)電機(jī)把發(fā)動(dòng)機(jī)的機(jī)械能換成電能并給電池再充電。</p><p><b>　　氣缸體：</b></p><p>　　氣缸體是發(fā)動(dòng)機(jī)的基本框架。發(fā)動(dòng)機(jī)的其他零件都安裝在它里面或者固定在它上。缸體里有氣缸，

16、水套和油道。曲軸也固定在氣缸體底部。除了頂置凸輪(OHC)發(fā)動(dòng)機(jī)以外，凸輪軸都安裝在氣缸體里面。在大多數(shù)汽車?yán)?，氣缸體由灰鑄鐵或者一種灰鑄鐵和其他金屬的合金(混合物)做成，例如鎳或鉻。氣缸體是鑄件。 </p><p>　　有些氣缸體，特別是在小汽車?yán)锏哪切际怯射X做成的。這種金屬比鑄鐵輕得多。但是，鑄鐵的耐磨性比鋁好。因此，在大多數(shù)鋁制發(fā)動(dòng)機(jī)的氣缸內(nèi)鑲有鑄鐵或者鋼的軸套。這些軸套叫做氣缸套。而有些氣缸體完全由

17、鋁做成。</p><p><b>　　氣缸蓋：</b></p><p>　　氣缸蓋固定在氣缸體的頂上，正像屋頂套在一所房子上面一樣。氣缸蓋下面與活塞頂上的空間形成燃燒室。最常見的氣缸蓋類型是半球形，楔形和準(zhǔn)半球形。這三種說法都是指燃燒室的形狀。氣缸蓋攜帶閥門，氣門彈簧和在搖臂桿上的搖臂，這部分的氣門傳動(dòng)機(jī)構(gòu)通過推桿工作。有時(shí)，凸輪軸直接安裝在氣缸蓋上并且不用搖臂控制閥

18、門工作。這被叫為頂置凸輪軸裝置。像氣缸體一樣，氣缸蓋是由鑄鐵或者鋁合金制成。</p><p><b>　　襯墊：</b></p><p>　　氣缸蓋與氣缸體用高強(qiáng)度的鋼螺栓縛連結(jié)。氣缸體和氣缸蓋之間的連接必須密封以便沒有燃燒的混合氣體泄漏。這通過使用氣缸蓋襯墊實(shí)現(xiàn)。這是一個(gè)夾層襯墊，即在兩片銅之間放一片石棉，這兩種材料都能禁得住在發(fā)動(dòng)機(jī)內(nèi)的高溫和高壓。</p&g

19、t;<p><b>　　油底殼：</b></p><p>　　油底殼通常由鋼沖壓形成。油底殼和氣缸體的下半部分一同被叫做曲軸箱；他們把曲軸封閉起來。潤(rùn)滑系統(tǒng)中的機(jī)油泵從油底殼抽取油并把油輸送到發(fā)動(dòng)機(jī)內(nèi)全部正在工作的部分。機(jī)油流出后又流回油底殼。因而在油底殼和發(fā)動(dòng)機(jī)工作零件之間有機(jī)油不斷流動(dòng)循環(huán)。</p><p><b>　　進(jìn)氣配氣定時(shí)：<

20、;/b></p><p>　　如果進(jìn)口門在進(jìn)氣行程的上止點(diǎn)打開并且在這次行程的下止點(diǎn)關(guān)閉，它將有180°的開度。氣門在180°轉(zhuǎn)角內(nèi)完全打開。然而氣門達(dá)到全開位置需要一定時(shí)間，完全關(guān)閉也需要一定時(shí)間。因此閥門在上止點(diǎn)(BTDC)之前被打開，在下止點(diǎn)(ABDC)之后關(guān)閉。</p><p>　　排氣配氣定時(shí)： </p><p>　　如果排氣

21、門在排氣行程的下止點(diǎn)打開并且在這次行程的上止點(diǎn)關(guān)閉，它將有180°的持續(xù)。但是像進(jìn)氣門一樣，排氣門需要時(shí)間到達(dá)充分打開和關(guān)閉的位置。因此排氣門在下止點(diǎn)之前打開，在上止點(diǎn)之后關(guān)閉。 </p><p><b>　　氣門重疊：</b></p><p>　　進(jìn)氣門在上止點(diǎn)前17°打開，排氣門在上止點(diǎn)后17°關(guān)閉。 因此，有34°的一

22、段時(shí)期，兩個(gè)閥門都是開的：(17°+ 17°= 34°)。這時(shí)期被稱為氣門重疊。排氣門的關(guān)閉和進(jìn)氣門的開啟重疊。在這個(gè)時(shí)候，新的混合氣推動(dòng)燃燒后的廢氣從排氣門排出。在渦輪增壓發(fā)動(dòng)機(jī)上氣門重疊角被保持在一個(gè)最小值。這就防止廢氣倒流入進(jìn)氣管。 </p><p><b>　　配氣機(jī)構(gòu)：</b></p><p>　　那些打開和關(guān)閉氣門的氣門傳動(dòng)

23、是為了協(xié)調(diào)四沖程的工作循環(huán)(使他們各自上下移動(dòng))。這些閥門運(yùn)動(dòng)必須正好在合適的時(shí)刻進(jìn)行。每個(gè)閥門的開啟由凸輪軸控制。</p><p>　　頂置凸輪軸氣閥傳動(dòng)：</p><p>　　凸輪是一在軸上的蛋形的金屬，通過曲軸協(xié)調(diào)旋轉(zhuǎn)。那金屬軸叫凸輪軸，在發(fā)動(dòng)機(jī)里的每個(gè)氣門一般有各自的凸輪。當(dāng)凸輪軸旋轉(zhuǎn)時(shí)，凸輪凸起的或者高點(diǎn)的位置，推動(dòng)氣門座。這行動(dòng)強(qiáng)迫閥門向下移動(dòng)。這過程能使進(jìn)氣門在進(jìn)氣行程打開，

24、或者排氣門在排氣行程打開。 </p><p>　　因?yàn)橥馆嗇S繼續(xù)旋轉(zhuǎn)，凸輪軸上的凸起部分離開氣門裝置。當(dāng)這發(fā)生時(shí)，氣門彈簧緊緊地關(guān)閉氣門口，叫做氣門座。</p><p>　　現(xiàn)代汽車發(fā)動(dòng)機(jī)里的閥門位于發(fā)動(dòng)機(jī)頂上的汽缸蓋。這被稱為頂置氣門(OHV)結(jié)構(gòu)。另外，當(dāng)凸輪軸位于汽缸蓋上面時(shí)，這種方式被稱為是頂置凸輪軸(OHC)結(jié)構(gòu)。一些高性能發(fā)動(dòng)機(jī)有兩個(gè)單獨(dú)的凸輪軸，分別負(fù)責(zé)開關(guān)進(jìn)氣門和排氣門。

25、這些發(fā)動(dòng)機(jī)被稱為雙頂置凸輪軸(DOHC)發(fā)動(dòng)機(jī)。</p><p><b>　　推桿氣閥傳動(dòng)：</b></p><p>　　凸輪軸也裝在發(fā)動(dòng)機(jī)底部的氣缸體內(nèi)。為了將凸輪的運(yùn)動(dòng)傳給氣門需要一些附屬裝置。</p><p>　　在這種布置中，凸輪凸角推動(dòng)凸輪挺桿。當(dāng)凸輪的凸角在凸輪挺桿下出現(xiàn)時(shí)，它推動(dòng)凸輪挺桿向上運(yùn)動(dòng)(離開凸輪軸)。凸輪挺桿推動(dòng)控制搖臂

26、的推桿。搖臂以通過它的中心為軸而旋轉(zhuǎn)。當(dāng)搖臂的一側(cè)上升，其另一側(cè)下降，正如一塊蹺蹺板一樣。搖臂向下移動(dòng)的那一邊推動(dòng)氣門桿以打開氣門。 </p><p>　　因?yàn)橥茥U氣閥傳動(dòng)有另外的部分，所以很難以高速運(yùn)轉(zhuǎn)。推桿發(fā)動(dòng)機(jī)一般在低速運(yùn)轉(zhuǎn)，從而產(chǎn)生比相同大小的頂置凸輪軸較少功率。(記住，功率反映了工作能力。) </p><p><b>　　氣門間隙：</b><

27、/p><p>　　當(dāng)發(fā)動(dòng)機(jī)處于壓縮行程和做功行程時(shí)，閥門必須緊緊地關(guān)閉以產(chǎn)生一個(gè)不透氣的氣封，以防止氣體逃離燃燒室。如果閥門不完全關(guān)閉，發(fā)動(dòng)機(jī)將不能發(fā)揮全部動(dòng)力。此外氣門頭易于被通過的熱氣體燃燒，這有可能使活塞頻繁沖擊打開的氣門，使發(fā)動(dòng)機(jī)嚴(yán)重?fù)p壞。 </p><p>　　所以閥門能完全關(guān)閉，氣門間隙在操作機(jī)構(gòu)內(nèi)是必須的。這意味著操作機(jī)構(gòu)必須離閥門足夠遠(yuǎn)以允許閥門通過氣門彈簧使其完全關(guān)閉

28、。但是，如果間隙太大，將引起金屬輕敲的噪音。</p><p><b>　　凸輪軸驅(qū)動(dòng)機(jī)構(gòu)：</b></p><p>　　在四行程循環(huán)時(shí)，每凸輪必須旋轉(zhuǎn)打開一閥門。記住，一個(gè)循環(huán)相當(dāng)于曲軸旋轉(zhuǎn)兩次。因此，凸輪軸必須以曲軸正好一半的速度旋轉(zhuǎn)。這用2：1的傳動(dòng)比完成。齒輪連接到凸輪軸的齒數(shù)是齒輪連接到曲軸的兩倍。齒輪連結(jié)有三種方式：</p><p>

29、<b>　?。?）皮帶傳動(dòng)</b></p><p>　　齒型帶能被使用。這樣的帶是由合成橡膠做成并且用內(nèi)部的鋼或者玻璃纖維絞合加強(qiáng)。皮帶上有齒，或者槽以嚙合并且驅(qū)動(dòng)傳動(dòng)齒輪上的齒。皮帶一般與頂置凸輪閥門傳動(dòng)一起被用在發(fā)動(dòng)機(jī)上。</p><p><b>　?。?）鏈傳動(dòng)</b></p><p>　　在一些發(fā)動(dòng)機(jī)上，金屬鏈被用

30、來連結(jié)曲軸和凸輪軸齒輪。大多數(shù)推桿發(fā)動(dòng)機(jī)和一些頂置凸輪軸發(fā)動(dòng)機(jī)都有鏈。</p><p><b>　?。?）齒輪傳動(dòng)</b></p><p>　　凸輪軸和曲軸齒輪可能被直接連結(jié)，或者相嚙合。這類操作聯(lián)動(dòng)通常被用在更老的六氣缸，直列發(fā)動(dòng)機(jī)上。</p><p>　　凸輪軸被鏈或者帶驅(qū)動(dòng)，使其朝著曲軸相同的方向轉(zhuǎn)動(dòng)。但是凸輪軸被曲軸齒輪直接驅(qū)動(dòng)，其將在

31、相反方向上轉(zhuǎn)動(dòng)。正時(shí)皮帶被使用，因?yàn)樗麄兓ㄙM(fèi)少于鏈子，而且噪音少。一條典型的正時(shí)皮帶由用玻璃纖維加強(qiáng)的氯丁橡膠(合成橡膠)做成的。</p><p><b>　　附件2：外文原文</b></p><p>　　belong engine</p><p>　　We know that both gasoline engines or diesel e

32、ngines, they all belong engine. all from the burning of fuel through the cylinder piston made from the campaign to promote the fuel conversion of chemical energy into mechanical energy driving the vehicle forward. So the

33、 working principle is generally the same.</p><p>　　Daily use as fuel itself, the highest energy density of diesel, liquefied natural gas nearly doubled over, more than 10% higher than gasoline. Compared with

34、 conventional gasoline, diesel not volatile, higher ignition point, the situation was not due to accidental fire or explosion. Because of the volatile and, if different, resulting in the use of two different fuels the en

35、gine ignition.</p><p>　　Gasoline Engine features : small size, light weight, good start.</p><p>　　Gasoline engines, the gas mixture into the cylinder, close to the end of the compression ignited

36、 by the spark plug. Therefore, the need for a gasoline engine when to control the spark plug ignition system. This system requires an accurate control of spark plugs and spark discharge energy of the moment, be able to e

37、nsure the normal gasoline engine. gasoline engine fuel supply system and ignition system is a high proportion of the gasoline engine fault location. In addition, the gasoline ignited l</p><p>　　The advantage

38、 lies in its small gasoline engine, light weight, low price; Start good, the speed at maximum power; Small vibration and noise work, therefore, passenger motor vehicles, particularly cars, has been widely used in gasolin

39、e engines. especially in the vast majority of our country's current production cars, as their gasoline engines are used on the power system.</p><p>　　The conventional diesel engine thermal efficiency and

40、 economy better characteristics :</p><p>　　Diesel use of compressed air and improve air temperature, air temperature over the spontaneous ignition of diesel. Then again injected into diesel, hybrid diesel sp

41、ray at the same time their ignition and combustion air. Therefore, no diesel engine ignition system. Meanwhile, the engine oil system is relatively simple and therefore the reliability of diesel engines than gasoline eng

42、ines as good.</p><p>　　From injuries caused by spontaneous combustion due to the restrictions and the need for diesel engine with a high compression ratio. Thermal efficiency and economy must be better than

43、the gasoline engine, while the power in the same circumstances, the engine torque, maximum power at low speed, suitable for use in the truck.</p><p>　　However, due to work pressure Diesel called on the struc

44、tural components with high strength and stiffness. So Diesel relatively bulky size; Diesel fuel pump with the nozzle to create high-precision, high costs; In addition, the engine crude, large vibration and noise; Diesel

45、easy evaporation in winter when cold starting problems.</p><p>　　Because of these features, previously used in diesel engines, medium radial truck.</p><p>　　The new development : small high-spee

46、d diesel engine emission standards has been achieved in Euc22 rope III.</p><p>　　Traditionally, due to relatively heavy diesel engine or gasoline engine power as indicators (low speed), noise, vibration high

47、er. Smoke and carbon particles (PM) emissions is fairly serious, very little has been favored by car.</p><p>　　But with the advances in technology in recent years Diesel, especially small high-speed diesel e

48、ngine is a new development of a number of advanced technologies, For example, electronic control DI, common rail, turbo-charged, in the cold light of technology, such as the use of diesel engines. The shortcomings of the

49、 original diesel engine to be a better solution. and the diesel engine's advantages in energy and CO2 emissions. including the gasoline engine is no way to replace all heat engines, ad</p><p>　　ICE is a

50、heat engine. Usually can burn the fuel used to be in : gasoline engine, gas and other types of aircraft. Because the gasoline engine light, low noise and environmental protection, it won the public good reputation, There

51、fore organic in its national economy and national defense projects has been more widely used. Engine Heat Transfer to a large extent the key to the economic gasoline engine, reliability and other important technical and

52、economic indicators. The gasoline engine load incre</p><p><b>　　Engine</b></p><p>　　The engine acts as the power unit. The internal combustion engine is most common: this obtains its

53、 power by burning a liquid fuel inside the engine cylinder. There are two types of engine :gasoline(also called a spark-ignition engine) and diesel(also called a compression-ignition engine).Both engines are called heat

54、engines; the burning fuel generates heat which causes the gas inside the cylinder to increase its pressure and supply power to rotate a shaft connected to the transmission.</p><p><b>　　Body</b>&l

55、t;/p><p>　　An automobile body is a sheet metal shell with windows, doors, a hood, and a trunk deck built into it. It provides a protective covering for the engine, passengers, and cargo. The body is designed to

56、 keep passengers safe and comfortable. The body styling provides an attractive, colorful, modern appearance for the vehicle.</p><p><b>　　Chassis</b></p><p>　　The chassis is an assemb

57、ly of those systems that are the major operating part of a vehicle. The chassis includes the transmission, suspension, steering, and brake systems.</p><p>　　Transmission systems ― conveys the drive to the wh

58、eels. The main components are clutch, gearbox, driveshaft, final drive, and differential.</p><p>　　Suspension― absorbs the road shocks.</p><p>　　Steering― controls the direction of the movement.

59、</p><p>　　Brake― slows down the vehicle.</p><p>　　Electrical Equipment</p><p>　　The electrical system supplies electricity for the ignition, horn, lights, heater, and starter. The e

60、lectricity level is maintained by a charging circuit. This circuit consists of the battery, alternator (or generator). The battery stores electricity. The alternator changes the engine's mechanical energy into electr

61、ical energy and recharges the battery.</p><p>　　Engine Block</p><p>　　The engine block is the basic frame of the engine. All other engine parts either fit inside it or fasten to it. It holds the

62、 cylinders, water jackets, and oil galleries.The engine block also holds the crankshaft, which fastens to the bottom of the block. The camshaft also fits inside the block, except on overhead-cam engines (OHC). In most ca

63、rs, this block is made of gray iron, or an alloy (mixture) of gray iron and other metals, such as nickel or chromium. Engine blocks are castings. </p><p>　　Some engine blocks, especially those in smaller ca

64、rs, are made of cast aluminum. This metal is much lighter than iron. However, iron wears better than aluminum. Therefore, the cylinders in most aluminum engines are lined with iron or steel sleeves. These sleeves are cal

65、led cylinder sleeves. Some engine blocks are made entirely of aluminum.</p><p>　　Cylinder Head</p><p>　　The cylinder head fastens to the top of the block, just as a roof fits over a house. The u

66、nderside forms the combustion chamber with the top of the piston. The most common cylinder head types are the hemi, wedge, and semi-hemi.All three of these terms refer to the shape of the engine's combustion chamber.

67、 The cylinder head carries the valves, valve springs and the rockers on the rocker shaft, this part of the valve gear being worked by the push-rods. Sometimes the camshaft is fitted directly int</p><p><b

68、>　　Gasket</b></p><p>　　The cylinder head is attached to the block with high-tensile steel studs. The joint between the block and the head must be gas-tight so that none of the burning mixture can es

69、cape. This is achieved by using cylinder head gasket. This is a sandwich gasket, i.e. a sheet of asbestos between two sheets of copper, both these materials being able to withstand the high temperature and pressures with

70、in the engine.</p><p>　　Oil Pan or Sump</p><p>　　The oil pan is usually formed of pressed steel. The oil pan and the lower part of the cylinder block together are called the crankcase; they encl

71、ose, or encase, the crankshaft. The oil pump in the lubricating system draws oil from the oil pan and sends it to all working parts in the engine. The oil drains off and runs down into the pan. Thus, there is constant ci

72、rculation of oil between the pan and the working parts of the engine.</p><p>　　Inlet Valve Timing</p><p>　　If the inlet valve opened at TDC of the intake stroke and closed at BDC of that stroke,

73、 it would have a duration of 180°.It would have remained open for half of a complete 360° revolution, or 180°. However, it takes some time for the valve to open to its full position. It also takes time for

74、 it to close tightly. Therefore the valve is opened before TDC (BTDC) and closed after BDC (ABDC).</p><p>　　Exhaust Valve Timing</p><p>　　If the exhaust valve opened at BDC at the beginning of t

75、he exhaust stroke and closed at TDC at the end of the exhaust stroke, it would have a duration of 180°. But like the inlet valve, the exhaust valve needs time to reach the full-open position, It also needs time to r

76、each the full-closed position. So the exhaust valve opens before BDC and closes after TDC.</p><p>　　Valve Overlap</p><p>　　The intake opens at 17° BTDC and the exhaust closes at 17° AT

77、DC. Thus, for a period of 34°, both of the valves are open: (17° + 17° =34°). This period of time is known as valve overlap. The closing of the exhaust valve laps over the opening of the intake valve.

78、 During this time, the first of the new mixture pushes the last of the burned gases out the exhaust valve. Valve overlap is held to a minimum on turbo-charged engines. This prevents the intake charge from being blown out

79、 the exhaust.</p><p>　　Valve Operation</p><p>　　To coordinate the four-stroke cycle, a group of parts called the valve train opens and closes the valves (moves them down and up, respectively). T

80、hese valve movements must take place at exactly the right moments. The opening of each valve is controlled by a camshaft.</p><p>　　Overhead camshaft (OHC) valve train</p><p>　　The cam is an egg-

81、shaped piece of metal on a shaft that rotates in coordination with the crankshaft. The metal shaft, called the camshaft, typically has individual cams for each valve in the engine. As the camshaft rotates, the lobe, or h

82、igh spot of the cam, pushes against parts connected to the stem of the valve. This action forces the valve to move downward. This action could open an inlet valve for an intake stroke, or open an exhaust valve for an exh

83、aust stroke.</p><p>　　As the camshaft continues to rotate, the high spot moves way from the valve mechanism. As this occurs, valve springs pull the valve tightly closed against its opening, called the valve

84、seat.</p><p>　　Valves in modern car engines are located in the cylinder head at the top of the engine. This is known as an overhead valve (OHV) configuration. In addition, when the camshaft is located over t

85、he cylinder head, the arrangement is known as an overhead camshaft (OHC) design. Some high-performance engines have two separate camshafts, one for each set of inlet and exhaust valves. These engines are known as dual ov

86、erhead camshaft (DOHC) engines.</p><p>　　Push-rod valve train</p><p>　　The camshaft also can be located in the lower part of the engine, within the engine block. To transfer the motion of the ca

87、m upward to the valve, additional parts are needed.</p><p>　　In this arrangement, the cam lobes push against round metal cylinders called cam follower. As the lobe of the cam comes up under the cam follower,

88、 it pushes the cam follower upward (away from the camshaft). The cam follower rides against a push rod, which pushes against a rocker arm. The rocker arm pivots on a shaft through its center. As one side of the rocker ar

89、m moves up, the other side moves down, just like a seesaw. The downward-moving side of the rocker arm pushes on the valve stem to open</p><p>　　Because a push-rod valve train has additional parts, it is more

90、 difficult to run at high speeds. Push-rod engines typically run at slower speeds and, consequently, produce less horsepower than overhead-camshaft designs of equal size. (Remember, power is the rate at which work is don

91、e.)</p><p>　　Valve Clearance</p><p>　　When the engine runs in compression stroke and power stroke, the valves must close tightly on their seats to produce a gas-tight seal and thus prevent the g

92、ases escaping from the combustion chamber. If the valves do not close fully the engine will not develop full power. Also the valve heads will be liable to be burnt by the passing hot gases, and there is the likelihood of

93、 the piston crown touching an open valve, which can seriously damage the engine.</p><p>　　So that the valves can close fully some clearance is needed in the operating mechanism. This means that the operating

94、 mechanism must be able to move sufficiently far enough away from the valve to allow the valves to be fully closed against its seat by the valve spring. However, if the clearance is set too great this will cause a light

95、metallic tapping noise.</p><p>　　Camshaft Drive Mechanism</p><p>　　Each cam must revolve once during the four-stroke cycle to open a valve. A cycle, remember, corresponds with two revolutions of

96、 the crankshaft. Therefore, the camshaft must revolve at exactly half the speed of the crankshaft. This is accomplished with a 2:1 great ratio. A gear connected to the camshaft has twice the number of teeth as a gear con

97、nected to the crankshaft. The gears are linked in one of three ways:</p><p>　　(1) Belt drive</p><p>　　A cog-type belt can be used. Such belts are made of synthetic rubber and reinforced with int

98、ernal steel or fiberglass strands. The belts have teeth, or slotted spaces to engage and drive teeth on gear wheels. A belt typically is used on engines with overhead-cam valve trains.</p><p>　?。?）Chain driv

99、e</p><p>　　On some engines, a metal chain is used to connect the crankshaft and camshaft gears. Most push-rod engines and some OHC engines have.</p><p>　?。?）Gearlchains drive</p><p>

100、;　　The camshaft and crankshaft gears can be connected directly, or meshed. This type of operating linkage commonly is used on older six-cylinder, inline engines.</p><p>　　A camshaft driven by a chain or belt

101、 turns in the same direction as the crankshaft. But a camshaft driven directly by the crankshaft gear turns in the opposite direction. Timing belts are used because they cost less than chains and operate more quietly. A