机电工程英语

1、Lesson 21: Introduction to Automobile,词汇讲解 课文分析 练习答案,本课教学目标,理解汽车差速器、燃油喷射器的作用； 掌握与汽车相关的专业词汇； 熟悉独立主格、伴随壮语等语法现象,Section ： words and phases,重点专业名词解析 词性转换 专有名词的通用含义,Now you will have 5 minutes to skim over the new words and phrases, marking the special words you cant understand,1. 重点专业名词解析,differential s

2、uspension transmission driving axle at the same time they must be free to revolve at different speeds when necessary (e.g., when rounding a curve, the outer wheel travels farther and thus must revolve faster than the inner wheel in order to prevent skidding,汽车差速器由装在驱动桥上的一套的齿轮组成。驱动桥两端的车轮必须互连，以便从同一个动力

3、源即传动轴上获取能量；同时，必要时，两个车轮必须能自由地以不同的速度旋转（例如，拐弯时，外侧的轮子比内侧的行驶的距离更远，为了避免打滑，故其转速应更快,These two requirements are met by the differential gearing. Furthermore, through it the rotating motion of the driving shaft is transmitted to the axle and the wheels. The axle is in two halves; to each half is attached a wh

4、eel at one end and, at the inner end, a gear. The end of the driving shaft is also equipped with a gear. By an ingenious arrangement (Fig.6.2) of these and other gears, together constituting the differential, a difference in speed of the two wheels is compensated for without a loss of tractive force

5、,使用差动传动装置能同时满足这两个要求。此外,通过差速传动装置可以把传动轴的旋转运动传递给驱动轴和车轮。驱动轴由两个半轴组成；每个半轴外端装了一个车轮，内端装了了一个(半轴)齿轮。传动轴的一端也装了一个齿轮。通过精巧地布置上述和其他的一些齿轮组成差速器，两个车轮的速度差异就能得到补偿，且不损失牵引力,左侧大图表示其基本结构。 右上图表示2侧半轴同步转动时，行星齿轮不转，而带着两侧半轴同步转动。 右下图表示当右侧半轴转速超过左侧半轴时，其极端情况是左半轴停止转动时，由于传动轴强迫盆齿以一定的速度继续转动，2个行星齿轮便会产生左右相反的转动，而该转动又会使右侧半轴在原来跟随盆齿转动的基础上又产生一

6、个向前的转动量。这时右半轴的转速来自于两部分原因：第一，盆齿的转动，第二，行星齿轮的转动。因此，行星齿轮组转动的结果相当于把不转动或转动慢的一侧半轴的转速传递给了另一侧半轴。所以，当盆齿转动速度一定的时候，两侧半轴的转速和是一个定值，而差速器的作用就是在这个前提下，使左右半轴的速度可以自由分配,A disadvantage of the conventional differential is that when one wheel is on a dry and the other on a slippery surface, the differential causes the whee

7、l on the slippery surface to revolve at double speed while the other wheel remains stationary. This hazard can be avoided by use of a limited slip differential, which feeds power to one wheel when the other wheel starts to slip and thus keeps the automobile moving,常见的差速器的缺点是：当一个车轮走在干硬的地面上而另一个车轮走在湿滑的

8、地面上时，差速器会导致走在打滑地面上的轮子转速加倍，而使另外一个轮子保持静止。使用防滑差速器则能避免出现这一危险情况，这种分速器在某个车轮开始打滑时只给另一个车轮供给能量，从而保持汽车移动,Oral English practice,Is a differential a part of driving axle? and whats its function? Do driving axle and driving shaft refer to the same thing? If not, whats the difference between them,Now we will come

9、 to the last paragraph, read it silently in 5 minutes, please,paragraph,Fuel injection system in an internal-combustion engine delivers fuel or a fuel-air mixture to the cylinders by means of pressure from a pump. It was originally used in diesel engines because of diesel fuels greater viscosity and

10、 the need to overcome the high pressure of the compressed air in the cylinders. A diesel fuel injector sprays an intermittent, timed, metered quantity of fuel into a cylinder, distributing the fuel throughout the air within,内燃机上的燃油喷射系统通过泵产生的压力来将油或油气混合物传递给汽缸。燃油喷射系统最早用在柴油机上，因为柴油的黏度较大,且需克服汽缸里受压缩空气的高压。柴

11、油喷射器间歇地、定时地将一定量的柴油喷洒到汽缸中，使燃油与空气充分混合,Fuel injection is also now used in gasoline engines in place of a carburetor. In gasoline engines the fuel usually is injected into the intake manifold and mixed with air, and the resulting mixture is delivered to the cylinder. Modern fuel injection systems use co

12、mputers to regulate the process. Fuel injection results in more efficient fuel combustion, improving fuel economy and engine performance and reducing polluting exhaust emissions,内燃机上的燃油喷射系统通过泵产生的压力来将油或油气混合物传递给汽缸。燃油喷射系统最早用在柴油机上，因为柴油的黏度较大,且需克服汽缸里受压缩空气的高压。柴油喷射器间歇地、定时地将一定量的柴油喷洒到汽缸中，使燃油与空气充分混合,Oral English practice,Fuel injection system can be used both in diesel engine and gasoline engine, however, is there any difference between them,Section ： exercises,