PROFESSIONAL ENGLISH UNIT 2 ENGINE MECHANICAL TEXT B Valve Systems
UNIT 2 ENGINE MECHANICAL TEXT B Valve Systems PROFESSIONAL ENGLISH
本次课学习内容 UNIT 2 ENGINE MECHANICAL TEXT B Valve Systems Operation of valve System WT--Toyota's Continuously Variable Valve Timing VTEC-Honda Variable Valve Timing and Lift Electronic Control MIVEC-Mitsubishi Innovative valve timing electronic control Electronic Valve Control System e Smart Valves
UNIT 2 ENGINE MECHANICAL TEXT B Valve Systems • Operation of Valve System • VVT—Toyota's Continuously Variable Valve Timing • VTEC—Honda Variable Valve Timing and Lift Electronic Control • MIVEC—Mitsubishi Innovative Valve timing Electronic Control • Electronic Valve Control System • Smart Valves 本次课学习内容
本次课学习目标 ●掌握可变气门定时机构主要部件的英文名 称 掌握可变气门定时机构的基本原理 ●掌握常用术语( phrases and expressIons 了解相关术语( related terms)
本次课学习目标 ⚫ 掌握可变气门定时机构主要部件的英文名 称 ⚫ 掌握可变气门定时机构的基本原理 ⚫ 掌握常用术语（phrases and expressions） ⚫ 了解相关术语（related terms）
NEW WORDS bump[bAmp]n撞击,(因撞击而起的)肿块;v碰,撞, 颠簸 cam [kaem]n凸轮 lobe[oub]n凸起 integral [intigral]a完整的,整体的,积分的 stem[ stem] n杆,茎 powertrain[ pauetrein]n动力系统,动力装置,传动系统 dyno [dainoun= dynamometer测功机,测力计 breathe[bri:o]v呼吸,发出 certification[se: tifi'keijan]n证明,鉴定,检验证明书 compromise[ kompremaiz]v&n妥协,折衷
NEW WORDS bump [bʌmp]n.撞击，（因撞击而起的）肿块；v.碰，撞， 颠簸 cam [kæm]n.凸轮 lobe [loub]n.凸起 integral ['intigrəl]a.完整的，整体的，积分的 stem [stem]n.杆，茎 powertrain ['pauətrein]n.动力系统，动力装置，传动系统 dyno ['dainou]n.=dynamometer测功机，测力计 breathe [bri:ð]v.呼吸，发出 certification [sə:tifi'kei∫ən]n.证明，鉴定，检验证明书 compromise ['kɔmprəmaiz]v. & n.妥协，折衷
essence [esns]n基本,本质,实质,精华,要素 puly[pu]n滑轮,带轮 helical [helike]a螺旋状的 spline[ splain] n花键,方栓 spool [spu: l]n 线轴,卷轴;滑阀;线圈 mpg= mile per gallon(英里/加仑) actuator [aektjueita]n执行器,执行元件 strategy ['straetiozi]n.策略,谋略 flexibility [fleks" biliti n灵活性,柔性,适应性 eager D"i:g]v渴望着,热心于 multiplex ['mAtipleks]a多元的,多重的,多样的;n多路传 输,多路通信
essence ['esns] n.基本，本质，实质，精华，要素 pulley ['puli] n.滑轮，带轮 helical ['helikəl] a.螺旋状的 spline [splain] n.花键，方栓 spool [spu:l] n.线轴，卷轴；滑阀；线圈 mpg = mile per gallon（英里/加仑） actuator ['æktjueitə] n.执行器，执行元件 strategy ['strætiʤi] n.策略，谋略 flexibility [fleksə'biliti] n.灵活性，柔性，适应性 eager ['i:gə] v.渴望着，热心于 multiplex ['mʌtipleks] a.多元的，多重的，多样的；n.多路传 输，多路通信
nominal [nominal] a.有名无实的;极微小的;标定的,额 定的 bus[bAs]n总线 innovation[ Inou vel∫onv改进,革新,创新,新发明[技 术,方法] residua[ ri'zidjualla剩余的,残余的
nominal ['nɔminəl] a. 有名无实的；极微小的；标定的，额 定的 bus [bʌs] n.总线 innovation [inou'vei∫ən] v.改进，革新，创新，新发明[技 术，方法] residual [ri'zidjuəl] a.剩余的，残余的
PHRASES AND EXPRESSIONS cam|obe凸轮的凸起部分 valve sten气门杆 variable valve timing(WT)可变气门定时 In essence本质上,实质上 spool valve滑阀 electronic valve control(Evc)电子式气门控制 centralized system集中系统 distributed system分布系统 camless engine无凸轮发动机 smart valve智能气门
cam lobe 凸轮的凸起部分 valve stem 气门杆 variable valve timing（VVT）可变气门定时 in essence 本质上，实质上 spool valve 滑阀 electronic valve control (EVC) 电子式气门控制 centralized system 集中系统 distributed system 分布系统 camless engine 无凸轮发动机 smart valve 智能气门 PHRASES AND EXPRESSIONS
Valve Systems Operation of valve System You have seen that the intake valve must be opened for the intake stroke, both valves must remain closed during the compression and power strokes, and the exhaust valve opens during the exhaust stroke. The designer must design a device to open and close the valves at the proper times The shaft will have an egg-shaped bump called a cam lobe. The cam lobe is machined as an integral part of the shaft. this shaft is called a camshaft The distance the valve will be raised, how long it will stay open, and how fast it opens and closes can all be controlled by the height and shape of the lobe [11 As you will see later, it is impractical to have the cam lobe contact the end of the valve stem itself. You have placed the camshaft some distance above the end of the valve stem
Valve Systems Operation of Valve System You have seen that the intake valve must be opened for the intake stroke, both valves must remain closed during the compression and power strokes, and the exhaust valve opens during the exhaust stroke. The designer must design a device to open and close the valves at the proper times. The shaft will have an egg-shaped bump called a cam lobe. The cam lobe is machined as an integral part of the shaft. This shaft is called a camshaft. The distance the valve will be raised, how long it will stay open, and how fast it opens and closes can all be controlled by the height and shape of the lobe [1]. As you will see later, it is impractical to have the cam lobe contact the end of the valve stem itself. You have placed the camshaft some distance above the end of the valve stem
When the camshaft is turn the lobes will not even touch the valve stem. the lifter is installed between the cam lobe and the valve stem. The upper end rides on the lobe and the lower end almost touches the valve stem the lifter slides up and down in a hole bored in the head metal that separates the valve stem from the camshaft [2] You have developed a method of opening and closing the valves. The next problem is how and at what speed to turn the camshafts. each valve must be open for one stroke. The intake valve is open during the intake stroke and remains closed during the compression, power, and exhaust strokes This would indicate that the cam lobe must turn fast enough to raise the valve every fourth stroke You can see that it takes one complete revolution of the cam lobe for every four strokes of the piston
When the camshaft is turn, the lobes will not even touch the valve stem. The lifter is installed between the cam lobe and the valve stem. The upper end rides on the lobe and the lower end almost touches the valve stem. The lifter slides up and down in a hole bored in the head metal that separates the valve stem from the camshaft [2]. You have developed a method of opening and closing the valves. The next problem is how and at what speed to turn the camshafts. Each valve must be open for one stroke. The intake valve is open during the intake stroke and remains closed during the compression, power, and exhaust strokes. This would indicate that the cam lobe must turn fast enough to raise the valve every fourth stroke. You can see that it takes one complete revolution of the cam lobe for every four strokes of the piston
Remember that four strokes of the piston require two revolutions of the crankshaft. You can say that for every two revolutions of the crankshaft the camshaft must turn once. If you are speaking of the speed of the camshaft, you can say that the camshaft must turn at one- half crankshaft speed If the crankshaft is turning and the camshaft must turn at one half crankshaft speed, it seems logical to use the spinning crankshaft to turn the camshaft. One very simple way to drive the camshaft would be by means of gears and a belt. One gear is fastened on the end of the crankshaft and the other is fastened on the end of the camshaft The large camshaft gear drives the smaller crankshaft gear through the belt If, for instance, the small gear on the crankshaft has 10 teeth and the large gear on the camshaft has 20 teeth, the crankshaft will turn the camshaft at exactly one-half crankshaft speed
Remember that four strokes of the piston require two revolutions of the crankshaft. You can say that for every two revolutions of the crankshaft, the camshaft must turn once. If you are speaking of the speed of the camshaft, you can say that the camshaft must turn at one-half crankshaft speed. If the crankshaft is turning and the camshaft must turn at onehalf crankshaft speed, it seems logical to use the spinning crankshaft to turn the camshaft. One very simple way to drive the camshaft would be by means of gears and a belt. One gear is fastened on the end of the crankshaft, and the other is fastened on the end of the camshaft. The large camshaft gear drives the smaller crankshaft gear through the belt. If, for instance, the small gear on the crankshaft has 10 teeth and the large gear on the camshaft has 20 teeth, the crankshaft will turn the camshaft at exactly one-half crankshaft speed