PROFESSIONAL ENGLISH UNIT 9 AUTOMATIC TRANSMISSIONS TEXT B/C Continuously Variable Transmissions (CVT)
UNIT 9 AUTOMATIC TRANSMISSIONS TEXT B/C Continuously Variable Transmissions (CVT) PROFESSIONAL ENGLISH
本次课学习内容 UNIT 9 AUTOMATIC TRANSMISSIONS TEXT B-C Continuously Variable Transmissions (CVT) History of the CvT ● Driving a car with a cv . How cVt Works Disadvantages of the CVT
UNIT 9 AUTOMATIC TRANSMISSIONS TEXT B-C Continuously Variable Transmissions (CVT) • History of the CVT • Driving a car with a CVT • How CVT Works • Advantages of the CVT • Disadvantages of the CVT 本次课学习内容
本次课学习目标 ●掌握无级变速器的有关英文专业词汇 ●掌握无级变速器的结构与工作原理 ●训练快速阅读能力,较高的阅读速度
本次课学习目标 ⚫ 掌握无级变速器的有关英文专业词汇 ⚫ 掌握无级变速器的结构与工作原理 ⚫ 训练快速阅读能力，较高的阅读速度
NEW WORDS sketch [sket门]v.勾画,绘略图 aka = also known as又叫,亦称 race rel v赛跑,疾驰,猛转,急转,使 空转 acceptance[ak' septan n接受,赞同,相信 accustom[e" kAssam]v使习惯于 floor [fi:] V在上铺(地板),(被困难)难倒 将(加速器等)踩到底 lurch n突然倾斜,摇摆,突然前倾 creep [kri:p]v爬行,蠕动,蹑手蹑脚,蔓延 robust r"bAst]a精力充沛的,坚固的,耐用的
NEW WORDS sketch [sket∫] v. 勾画，绘略图 a.k.a. =also known as又叫，亦称 race [reis] v.赛跑， 疾驰， 猛转，急转，使 空转 acceptance [ək'septən s] n.接受， 赞同， 相信 accustom [ə'kʌstəm] v.使习惯于 floor [flɔ:] v.在...上铺(地板)， (被困难)难倒， 将（加速器等）踩到底 lurch [lə:t∫] n.突然倾斜， 摇摆，突然前倾 creep [kri:p] v.爬行， 蠕动，蹑手蹑脚，蔓延 robust [rə'bʌst] a.精力充沛的，坚固的，耐用的
PHRASES AND EXPRESSIONS continuously variable无级变速器(英文缩写为cvT transmission call up 召唤,提取
PHRASES AND EXPRESSIONS continuously variable transmission 无级变速器（英文缩写为CVT） call up 召唤，提取
Continuously Variable Transmissions(CVD) A continuously variable transmission or Cvt, is a type of automatic transmission that provides more useable power, better fuel economy and a smoother driving experience than a traditional automatic History of the CVT Leonardo da vinci sketched the first cvt in 1490. dutch automaker daf first started using CVTs in their cars in the late 1950s, however technology limitations made cvis unsuitable for engines with more than around 100 horsepower. In the late 80s and early 90s, Subaru offered a Cvt in their Justy mini-car, while Honda used one in the high-mileage honda Civic hX of the late 90s Improved Cvis capable of handling more powerful engines were developed in the late 90s and 2000s and cvs can now be found in cars from nissan audi honda ford gm, and other automakers
Continuously Variable Transmissions (CVT) A continuously variable transmission, or CVT, is a type of automatic transmission that provides more useable power, better fuel economy and a smoother driving experience than a traditional automatic. History of the CVT Leonardo Da Vinci sketched the first CVT in 1490. Dutch automaker DAF first started using CVTs in their cars in the late 1950s; however technology limitations made CVTs unsuitable for engines with more than around 100 horsepower. In the late 80s and early 90s, Subaru offered a CVT in their Justy mini-car, while Honda used one in the high-mileage Honda Civic HX of the late 90s. Improved CVTs capable of handling more powerful engines were developed in the late 90s and 2000s, and CVTs can now be found in cars from Nissan, Audi, Honda, Ford, GM, and other automakers
Driving a car with a CVt The controls for a cvt are the same as an automatic no clutch pedal and a p-R-N-D-L-style shift pattern But while an automatic transmission has a set number of gear ratios (a.k.a. speeds), usually 4, 5 or 6, the cvt can constantly change the relationship of engine speed to car speed. When driving a car with a CVt, you never hear or feel the transmission shift--it simply raises and lowers the engine speed as needed, calling up higher engine speeds(or RPms) or better acceleration and lower rPMs for better fuel economy while cruIsing When you step on the accelerator, the engine races as it would with a slipping clutch or a failing automatic transmission This is normal - the cvt is adjusting the engine speed to provide optimal power for acceleration
Driving a car with a CVT The controls for a CVT are the same as an automatic: No clutch pedal and a P-R-N-D-L-style shift pattern. But while an automatic transmission has a set number of gear ratios (a.k.a. speeds), usually 4, 5 or 6, the CVT can constantly change the relationship of engine speed to car speed. When driving a car with a CVT, you never hear or feel the transmission shift—it simply raises and lowers the engine speed as needed, calling up higher engine speeds (or RPMs) for better acceleration and lower RPMs for better fuel economy while cruising. When you step on the accelerator, the engine races as it would with a slipping clutch or a failing automatic transmission. This is normal—the CVT is adjusting the engine speed to provide optimal power for acceleration
How cvt Works Traditional transmissions use a gearset that provides a given number of ratios(or speeds ). The transmission(or the driver) shifts gears to provide the most appropriate ratio for a given situation Lowest gears for starting out, middle gears for acceleration and passing and higher gears for fuel-efficient cruIsing Dhpu驶y Steel beit Fig 9-6 Driven pulley CVT low gear aver-drve ge邸ar operation
How CVT Works Traditional transmissions use a gearset that provides a given number of ratios (or speeds). The transmission (or the driver) shifts gears to provide the most appropriate ratio for a given situation: Lowest gears for starting out, middle gears for acceleration and passing, and higher gears for fuel-efficient cruising. Fig.9-6 CVT operation
Thoug h there are several types of CvTs, most cars use a pair of variable-diameter pulleys, each shaped like a pair of opposing cones with a metal belt or chain running between them(Fig.9-6)[1]. One pulley is connected to the engine(input shaft), the other to the drive wheels (output shaft). The halves of each pulley are moveable; as the pulley halves come closer together the belt is forced to ride higher on the pulley, effectively making the pulley's diameter larger. Changing the diameter of the pulleys varies the transmission 's ratio(the number of times the output shaft revolves for revolution of the engine), in the same way that a 10-speed bike routes the chain over larger or smaller gears to change the ratio Making the input pulley smaller and the output pulley larger gives a low ratio (a large number of engine revolutions producing a small number of output revolutions) for better low-speed acceleration. as the car accelerates the pulleys vary their diameter to lower the engine speed as car speed rises
Though there are several types of CVTs, most cars use a pair of variable-diameter pulleys, each shaped like a pair of opposing cones, with a metal belt or chain running between them(Fig.9-6) [1]. One pulley is connected to the engine (input shaft), the other to the drive wheels (output shaft). The halves of each pulley are moveable; as the pulley halves come closer together the belt is forced to ride higher on the pulley, effectively making the pulley's diameter larger. Changing the diameter of the pulleys varies the transmission's ratio (the number of times the output shaft revolves for revolution of the engine), in the same way that a 10-speed bike routes the chain over larger or smaller gears to change the ratio. Making the input pulley smaller and the output pulley larger gives a low ratio (a large number of engine revolutions producing a small number of output revolutions) for better low-speed acceleration. As the car accelerates, the pulleys vary their diameter to lower the engine speed as car speed rises
This is the same thing a conventional automatic or manual transmission does but while a conventional transmission changes the ratio in stages by shifting gears, the CvT continuously varies the ratio- hence the name " continuously variable transmission Advantages of the cvt Engines do not develop constant power at all speeds, they have specific speeds where torque, horsepower and fuel efficiency are at their highest levels. Because there are no gears to tie a given road speed directly to a given engine speed the cvt can vary the engine speed as needed to access maximum power as well as maximum fuel efficiency
This is the same thing a conventional automatic or manual transmission does, but while a conventional transmission changes the ratio in stages by shifting gears, the CVT continuously varies the ratio - hence the name "continuously variable transmission". Advantages of the CVT Engines do not develop constant power at all speeds; they have specific speeds where torque, horsepower and fuel efficiency are at their highest levels. Because there are no gears to tie a given road speed directly to a given engine speed, the CVT can vary the engine speed as needed to access maximum power as well as maximum fuel efficiency
