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1、复习o提问（教师说发动机汉语部件名称，同学回答英文名称）o用英语说明内燃机分类方式和类别oWhat are four strokes in a four-stroke-cycle engine?砧药饯揪浙端阮诽镊扦黎惕鼓公彝别利稍候射尧办掸弊胰桨唐筒豹尹懈撂汽车专业英语课件-3 chapter 2.4-2.5汽车专业英语课件-3 chapter 2.4-2.5学习内容学习内容本次课学习内容、目标和重点难点本次课学习内容、目标和重点难点学习目标学习目标难点重点难点重点2.4 Pistons, Connecting Rods and Crankshaft2.5 Valve System1.1.掌握
2、曲柄连杆机构主要组成、零件英文名掌握曲柄连杆机构主要组成、零件英文名称；称；2.2.了解了解VVTVVT系统的主要功能系统的主要功能1.1.重点为记忆曲柄连杆机构主要组成、零件重点为记忆曲柄连杆机构主要组成、零件英文专业术语英文专业术语2.2.难点需要记忆的生词偏多难点需要记忆的生词偏多3.3.汉译准确表达也是难点汉译准确表达也是难点境捣蠕相沧透地辊渊深葛细邓煮呀窜引郑梯绪窒编苞伊竭让亡乱眶窗析谚汽车专业英语课件-3 chapter 2.4-2.5汽车专业英语课件-3 chapter 2.4-2.5Chapter 2 Internal Combustion Engine2.4 Pistons,
3、 Connecting Rods and Crankshaft bearingbrin.轴承承journal:nln.轴颈throwroun.& v.投投掷，扔；，扔；n.投投掷距离，偏心距离，偏心距离，距离，摆幅；（幅；（pl.）曲柄）曲柄attachttv.附着，附着，连接，固定（接，固定（to）reciprocatingrisiprkeitia.往复的往复的2.4.1 New Words and Phrases宵店雀盘舜威终羽哥番揽橙抗矿辆暂尊炼德贬灌遮贱权卫蝎医餐愉柯肄澳汽车专业英语课件-3 chapter 2.4-2.5汽车专业英语课件-3 chapter 2.4-2.5 2.4.1
4、 Piston and connecting rodThe piston must move down through the cylinder to produce a vacuum to draw a fuel charge into the cylinder. It then travels up in the cylinder and compresses the mixture. When the mixture is fired, the pressure of the expanding gas is transmitted to the top of the piston. T
5、his drives the piston back down through the cylinder with great force, transmitting the energy of the expanding gas to the crankshaft. The piston then travels up through the cylinder and exhausts the burned fuel charge.Pistons are usually made of aluminum. Often, aluminum pistons are tin-plated to a
6、llow proper break-in when the engine is started. Aluminum pistons can be forged, but they are more commonly cast. Cast iron is a good material for pistons used in a slow-speed engine. It has excellent wear characteristics and will provide good performance. Chapter 2 Internal Combustion Engine2.4 Pis
7、tons, Connecting Rods and Crankshaft 2.4.2 Text华哀崔舔滔渝课慈删旦撵厢邀厩粥沿稍即钟知腮缆懒撑赛逃镍椅季汞季豫汽车专业英语课件-3 chapter 2.4-2.5汽车专业英语课件-3 chapter 2.4-2.5Fig.2-5 Pistons, connecting rods and crankshaft宽莆箭射愚遵涯视彻薪间佬翘岳哄潭辫避惰姜雕促辑筑味晋幕胚喀玉臣廉汽车专业英语课件-3 chapter 2.4-2.5汽车专业英语课件-3 chapter 2.4-2.5 As the name implies, connecting rods
8、are used to connect pistons to the crankshaft (Fig.2-5). The upper end of the rod has a hole through it for the piston pin. The bottom of the large end of the connecting rod (Fig.2-6) must be removed so the rod can be installed on the crankshaft journal. The section that is removed is called the con
9、necting rod cap. Connecting rods are normally made of alloy steel. They are drop-forged to shape and then machined.Fig.2-6 Connecting rodChapter 2 Internal Combustion Engine2.4 Pistons, Connecting Rods and Crankshaft 始仇鄂芦荆弥郎何欲旋旨蹭孙榆混辖甭谁憾搞内废录丑茶涣镊趁嘎犊帮姓汽车专业英语课件-3 chapter 2.4-2.5汽车专业英语课件-3 chapter 2.4-2.
10、5 2.4.2 Crankshaft The engine crankshaft (Fig.2-7) provides a constant turning force to the wheels. It has throws to which connecting rods are attached, and its function is to change the reciprocating motion of the piston to a rotary motion to drive the wheels. Crankshafts are made of alloy steel or
11、 cast iron. The crankshaft is held in position by a series of main bearings. The maximum number of main bearings for a crankshaft is one more than the number of cylinders. It may have fewer main bearings than cylinders.Chapter 2 Internal Combustion Engine2.4 Pistons, Connecting Rods and Crankshaft 拱
12、钮铜皋桐寐粗号微且攀汐嚎怎掺踢羡夯韦跌袍热铃狠抽驱杭彪救吻妇丘汽车专业英语课件-3 chapter 2.4-2.5汽车专业英语课件-3 chapter 2.4-2.5 Most engines use precision insert bearings that are constructed like the connecting rod bearings, but are somewhat larger. In addition to supporting the crankshaft, one of the main bearings must control the forward a
13、nd backward movement.Fig.2-7 Crankshaft蕉耐庇奉浸懦祸扼弓咆瞒蛙符只秩锥筛桓溉驹瞥靖翁稍武识慎那皿户趋阴汽车专业英语课件-3 chapter 2.4-2.5汽车专业英语课件-3 chapter 2.4-2.5 Chapter 2 Internal Combustion Engine2.5 Valve System lifterliftn.挺杆挺杆clearanceklirnsn.间隙隙2.5.1 New Words and Phrases准匹肾薯巍昂葡义狡姆舞茹万瘟到洲剿核幼则柴萝愿瑶霸瘫累斗笋奸到颂汽车专业英语课件-3 chapter 2.4-2.5汽车
14、专业英语课件-3 chapter 2.4-2.5 The camshaft must turn at one-half crankshaft speed. The camshaft is linked with crankshaft by one of three ways: belt drive, chain drive and gear drive. The main components of the valve system are: Camshaft. It is used to open and close the valves. Generally only one camsha
15、ft is used in most engines. Newer engines are increasingly equipped with two or more camshafts (Figure 2-8). Valves. Each engine cylinder ordinarily has two valves. However, modern engines often use four valves per cylinder (two intake valves and two exhaust valves). In order to prevent burning, the
16、 valve must give off heat to the valve seat and to the valve guide. The valve must make good contact with the seat and must run with minimum clearance in the guide.Chapter 2 Internal Combustion Engine2.5 Valve System 2.5.2 Text泵宅骨谚幂孵键型遍截请逛虎韦寒惕二怯间钨帖碎粮珍诧湍蜘臃荡械熟寐汽车专业英语课件-3 chapter 2.4-2.5汽车专业英语课件-3 chap
17、ter 2.4-2.5 Valve lifters. Mechanical valve lifters were used in older engines. Most valve trains that contain mechanical lifters have some provision for adjusting clearance. Hydraulic valve lifters perform the same job as mechanical lifters. However, hydraulic lifters are self-adjusting, operate wi
18、th no lifter-to-rocker arm clearance, and uses engine oil under pressure to operate. Hydraulic lifters are quiet in operation.Chapter 2 Internal Combustion Engine2.5 Valve System 匀徒亢犊版于赐亥长浊览烯绰阔佑睁每眩嫩疥巳径负缔臻帝笑兆奢罚窑镣汽车专业英语课件-3 chapter 2.4-2.5汽车专业英语课件-3 chapter 2.4-2.5Fig.2-8 Dual overhead camshaft（DOHC）笼
19、拼滨畜螟杆槛掌哭禁揭嫩拳跑鞠三震忧刚铰喇冠骆悠抽编咕树瞒酋静凝汽车专业英语课件-3 chapter 2.4-2.5汽车专业英语课件-3 chapter 2.4-2.5补充：Three types of camshaft drive凸轮轴三种传动方式：凸轮轴三种传动方式：Belt drive 带传动带传动Gear drive 齿轮传动齿轮传动Chain drive 链传动链传动私鞭掇份候纺枉莎睫菏凋耽柑谋班再钦搭迸来光语嘎卢裸莎座届叮零耽韶汽车专业英语课件-3 chapter 2.4-2.5汽车专业英语课件-3 chapter 2.4-2.5 variable valve timing syst
20、em eliminates the compromise of conventional valve timing with the introduction of VVT. By continuously varying intake valve timing (up to 60 crank angle degrees), Toyota optimizes low- to mid-speed torque, improves fuel economy and lowers emissions without having a negative impact on idle. In essen
21、ce, the system controls valve overlap, which means it can eliminate it completely for a glass smooth idle, or maximize it to boost volumetric efficiency and reduce pumping lossesthis translates into power, economy and cleaner running at all engine speeds. 补充： Continuously Variable Valve Timing （CVVT
22、）肿斜享殆功干谆像澳碳辩茸妇省肘泊步臆苹睫氢赠霄羊棺涕剂诺椎滞东滓汽车专业英语课件-3 chapter 2.4-2.5汽车专业英语课件-3 chapter 2.4-2.5 The heart of the system is the intake cam pulley, which consists of an inner and outer section. The inner portion is fixed to the camshaft and nests inside the belt-driven outer pulley via helical spline gears. An
23、electronically controlled hydraulic piston moves the pulley halves relative to one another, causing the cam portion to rotate within the outer pulley. This rotation advances or retards intake valve timing. A spool valve reacting to signals from the ECU controls hydraulic pressure.住距涟间宝汤堰暇秒夏缀糟无士今猛搪臻虐
24、璃糊透傻烤凛茁劫其催躁凝坎汽车专业英语课件-3 chapter 2.4-2.5汽车专业英语课件-3 chapter 2.4-2.5品任挞慰俱逮妻灿毫俞椰但隙鼠罐苹窃似酋侨疫败弥端悄寞淬妓葱滔锦斥汽车专业英语课件-3 chapter 2.4-2.5汽车专业英语课件-3 chapter 2.4-2.5碉馈总漳翁写聪却驳或等肤苟哗藩阐强棉栋馒镰寇荧沮酉连却配恃午狂愤汽车专业英语课件-3 chapter 2.4-2.5汽车专业英语课件-3 chapter 2.4-2.5VaneCama vane-type adjuster 狂汝包宾瘟立庇艾疫搞戍侥祥宗夸胖皱梗弥撒烈竞我双妮渝晌咨姆锥峙膜汽车专业英语课件-3 chapter 2.4-2.5汽车专业英语课件-3 chapter 2.4-2.5小结与作业o掌握内燃机主要部件的英文名称和有关术语 o阅读并记住黑体字专业词汇；o阅读补充内容，提出疑难问题序步键山步函僻雀搀电秧胀碗墓颇咋袄迈缕性白世葛邮社订鸿浮肇蒲聊歪汽车专业英语课件-3 chapter 2.4-2.5汽车专业英语课件-3 chapter 2.4-2.5
