ENGINE MECHANICAL 车辆工程专业英语教学PPT课件.pptx

UNIT 2 ENGINE MECHANICAL TEXT B Valve Systems ? Operation of Valve System ? VVT—Toyotas 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;本次课学习目标;NEW WORDS;essence [esns] n.基本，本质，实质，精华，要素 pulley [puli] n.滑轮，带轮 helical [helik?l] 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 [?ktjueit?] n.执行器，执行元件 strategy [str?ti?i] n.策略，谋略 flexibility [fleks?biliti] n.灵活性，柔性，适应性 eager [i:g?] v.渴望着，热心于 multiplex [m?tipleks] a.多元的，多重的，多样的；n.多路传输，多路通信;nominal [n?min?l] a. 有名无实的；极微小的；标定的，额 定的 bus [b?s] n.总线 innovation [inouvei∫?n] v.改进，革新，创新，新发明[技术，方法] residual [rizidju?l] a.剩余的，残余的 ;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 ;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 in