Chapter3Engine(2.6)说课.pptVIP

Basic words(1): Operating conditions: Basic words(３): 11) Gasoline direct injection（GDI）: * SEA—Special English for Automobile Chapter 2 internal combustion engine * Review 1: What’s the meaning of the air/fuel ratio (A/F)? The proportion of air to fuel. *A/F is stated in term of weight, different fuel has different ratio. Gasoline : Gasoline must vaporize easily. This characteristic, called volatility, is important. However, it must not vaporize too easily, or it will turn to vapor inside the fuel tank or fuel lines. Inside the fuel line, fuel vapor may block the flow of liquid gasoline. This is called vapor lock. Vapor lock is common in fuel lines where the inlet side of the pump is exposed to high temperatures. 汽油应易于蒸发，这个重要的特性称为挥发性。但是汽油也不能挥发得过快，不然它会在油箱或油管里转变为蒸气。在油管中汽油蒸气会阻碍液态汽油的流动，这称为气阻。汽油泵的入口处承受着高温，就经常出现气阻。 Increasing the pressure of the fuel mixture in the combustion chamber before ignition helps to increase the power of an engine. This is done by compressing the fuel mixture to a smaller volume. Higher compression ratios not only boost power but also give more efficient power. But as the compression ratio goes up, knocking tendency increases. 在点火前增加燃烧室内可燃混合气的压力有助于提高发动机的功率，这是通过把可燃混合气压缩到一个极小的体积来实现的。高的压缩比不仅增加发动机的功率，而且会带来更多的有效功率。但随着压缩比的增加，爆震的可能性也会增加。 2) gasoline: 3) gasoline: Two primary standard reference fuels, normal heptane and iso-octane arbitrarily assigned 0 and 100 octane number, respectively, are then blended to produce the same knock intensity as the test sample. The percentage of isooctane in blend is considered the octane number of the test sample. Thus, if the matching reference blend is made up of 15% n-heptane and 85% isooctane, the test sample is rated 85 motor or research octane number, according to the test method used. 两种基准参考燃料正庚烷和异辛烷分别被定义成辛烷值为0和辛烷值为100，将它们混合产生与实验样本相等敲缸强度的爆震。混合物中异辛烷的百分比就认为是实验样本的辛烷值。这样，依照实验方法，如果匹配的混合物由15%的正庚烷和85%异辛烷组成，那么按照所用的实验方法，对比实验样本的辛烷值就是85。 fuel tank 油箱 fuel filter 汽油滤清器 fuel pump 汽油泵 Carburetor (mix) 化油