【正文】 銷。發(fā)動(dòng)機(jī)內(nèi)所有的曲軸重量必須盡可能一致，但不是必須相等。它必須非常堅(jiān)硬，以承受做功行程的力而不發(fā)生彎曲。機(jī)體底部蓋有油 底殼或者叫集油器。 氣缸的直徑叫做發(fā)動(dòng)機(jī)的內(nèi)徑。 （ 1）進(jìn)氣沖程 隨著活塞向下移動(dòng)，可燃油氣混合氣通過開啟的進(jìn)氣門進(jìn)入氣缸。 天津職業(yè)技術(shù)師范大學(xué) 2021屆本科生畢業(yè)設(shè)計(jì) （ 3）做功沖程 混合氣燃燒膨脹產(chǎn)生的壓力使氣壓上升到 ，氣缸內(nèi)的活塞開始被推動(dòng)，排氣門在接近下止點(diǎn)時(shí)打開。發(fā)動(dòng)機(jī)的氣缸越多，每轉(zhuǎn)的做功行程就越長。這種發(fā)動(dòng)機(jī)通常是風(fēng)冷的，在保時(shí)捷、大眾 等車型上長見到，但也有用水冷的。大多數(shù) 4 缸和六缸發(fā)動(dòng)機(jī)用這種設(shè)計(jì)方案。 只要發(fā)動(dòng)機(jī)運(yùn)轉(zhuǎn)，氣缸的四個(gè)沖程就周而復(fù)始的不停重復(fù)。進(jìn)氣門直到下止點(diǎn)后 50176。根據(jù)發(fā)動(dòng)機(jī)的型號(hào)，一個(gè)工作 循環(huán)需要兩個(gè)或四個(gè)沖程來完成。下面連著連桿。氣缸中的活塞是上上下下的移動(dòng)的，它使往復(fù)循環(huán)的發(fā)動(dòng)機(jī)產(chǎn)生動(dòng)力。在做功行程中，連桿推動(dòng)連桿軸頸，因此曲軸旋轉(zhuǎn)。如果連 桿蓋混淆，軸承將運(yùn)轉(zhuǎn)不良。隨著活塞在氣缸內(nèi)上下運(yùn)動(dòng)，銷在孔內(nèi)來回運(yùn)動(dòng)。腳踏板就像連桿；它連著你的腿。此時(shí)，活塞和環(huán)磨損最小。然而，鋁作為汽缸體材料來說較軟，鋁的磨損也非常快。當(dāng)金屬溶液冷卻后，將模型打破拿走，只剩下了一個(gè)粗糙的汽缸體。 （ 6）活塞銷。 其它類型往復(fù)式發(fā)動(dòng)機(jī)的的代表是離心的，有斜向的盤子，或在曲軸上有一個(gè)凸輪機(jī)構(gòu)。 (7)安全的工作性能。 內(nèi)燃機(jī)有好幾種類型：兩沖程或四沖程的活塞發(fā)動(dòng)機(jī)，渦輪發(fā)動(dòng)機(jī)，自由活塞的發(fā)動(dòng)機(jī)。天津職業(yè)技術(shù)師范大學(xué) 2021屆本科生畢業(yè)設(shè)計(jì) Engine Fundamentals Automobiles have been operated successfully by electric motors ,steam engines ,and internal bustion engines .The internal bustion engine burns fuel within its cylinders and converts the expanding force of the burning fuel ,or bustion, into a rotary force used to propel the vehicle. There are several types of internal bustion engines: twoand fourcycle reciprocating piston engines ,gas turbine engines .However ,fourcycle reciprocating engines have been refined to such a degree that they have almost plete dominance of the automotive field .Engines of other types are described in Chapter 18 ,Diesel and Other Engines. Many things are demanded of an engine used to propel an automobile. Some of the requirements are: （ 1） Ease of starting. （ 2） Reliability. （ 3） Power. （ 4） Responsiveness. （ 5） Economy in fuel ,oil ,and ,repairs. （ 6） Ease of handling. （ 7） Quiet operation. Some of these factors conflict .For example ,a great amount of power can be had from an engine of sufficient size, but a supersize engines is not economical to operate .Therefore ,all automobile engines are a promise in order to obtain the desirable bination of performance and economy. Engine fuels Internal bustion engines can be made to operate on almost anythi ng that can be converted into a bustible gas, such as wood ,coal, alcohol, vegetable oils, mineral oils, etc. However, because of convenience, a variety of petroleum products are monly used as fuel :gasoline, kerosene ,fuel oil ,liquefied petroleum gas (LPGas) ect. What kerosene ,fuel oil ,or LPGas is used it is necessary to alter the design of the engine to achieve efficient operation. 天津職業(yè)技術(shù)師范大學(xué) 2021屆本科生畢業(yè)設(shè)計(jì) Engine Deign Gasoline engines used in automotive vehicles are of two basic types :fourcycle engines and twocycle engines .Either type may be watercooled ,or aircooled .Four ,six, and eightcylinder engines are mon However, three, five, ten ,and twelvecylinder engine are available. Almost all automobile engines have more than one cylinder. These cylinders can be arranged in an inline ,opposed ,or Vtype configuration. Engines for other purpose ,such as aviation, are arranged as radial, inverted inline ,inverted V, and Xshaped configurations. Reciprocating Engines In the typical automobile engine, a piston reciprocates (moves back and forth) within each cylinder. Each piston is connected to the crankshaft by means of a link known as a connecting rod. Other types of reciprocating engines substitutes an eccentric, an inclined plate ,or a cam mechanism for the crankshaft .The piston engine has no crankshaft or connecting rods. Engine Components The typical automotive engine is made up of several essential ponents. These ponents are designed to provide efficient and reliable engine operation .The basic ponents in a fourcycle automotive engine include the following: （ 1） Cylinder block. （ 2） Crankshaft. （ 3） Pitons. （ 4） Piston rings. （ 5） Connecting rods. （ 6）