Chapter2 Introduction to Engines

In trying to produce more efficient vehicles, American manufacturers put four-cylinder and other small engines into their cars, instead of large eight-cylinder engines. Some basic engine systems like carburetors and ignition breaker points were replaced by electronic fuel injection and electronic ignition systems.

By the mid-1980s, the American automobile had gained a measure of self-control over emissions and fuel efficiency through the use of computers and other electronics. Fuel and air were carefully monitored and consumed in proportions that maximized the performance of the smaller engines while minimizing the production or harmful pollutants.

After a prolonged period of economic growth in the 1980s, the demand for good performance was once again a shaping force in automotive design. Electronic sensors are now used to monitor engine functions. Computerized engine control systems control air and fuel delivery, ignition timing, emission systems operation, and a lot of other related operations. The result is a clean-burning, fuel-efficient, and powerful engine. Examples of late-model, high-tech, high-performance engines are the Northstar engine from General Motors and the DOHC 4.6-liter engine from Ford Motor Company. These engines have approximately 260 cubic inches (4.2 liters) and put out about 300 horsepower. They provide enough power to have these cars accelerate at nearly the same rate as (or quicker than) the larger-engined cars of the 1960s. They do this while achieving at least four times the gas mileage. They also do this in cars that corner and stop very well.

In recent years, the way horsepower is measured has changed. As a result, it seems as though today's engines are weaklings compared to those of yesterday; 300 horsepower appears to be nothing compared to the 400+ horsepower that was available in the 1960s. That thinking is wrong: 400 horsepower in the 1960s is worth about 270 horsepower today. It took 400+ cubic inches (6.5 liters) to produce that much power; now we get that much power from much smaller engines. The difference is Gross (old) versus Net (new) Horsepower!

Perhaps the thing that has brought about the greatest change in the automotive industry is the computer. Not only are engine support systems controlled by computers, nearly every other major system on a car has some sort of electronic control.

Today's automotive engines can be classified in several ways depending on the following design features:

■ Operational cycles. Most technicians will generally come in contact with only four-stroke engines. However, a few older cars have used and some cars in the future will use a two-stroke engine.

■ Number of cylinders(Figure 2-1). Current engine designs include 3-, 4-, 5-, 6-, 8-, 10-, and 12-cylinder engines.

■ Cylinder arrangement(Figure 2-2). An engine can be flat (opposed), inline, or V-type. Other more complicated designs have also been used.

■ Valve train type. Engine valve trains can be either the overhead camshaft (OHC) type or the camshaft in-block overhead valve (OHV) type. Some engines separate camshafts for the intake and exhaust valves. These are based on the OHC design and are called double overhead camshaft (DOHC) engines. V-type DOHC engines have four camshafts——two on each side.

■ Ignition type. There are two types of ignition systems: spark and compression. Gasoline engines use a spark ignition system. In a spark ignition system, the air-fuel mixture is ignited by an electrical spark. Diesel engines, or compression ignition engines, have no spark plugs. A diesel engine relies on the heat generated as air is compressed to ignite the air-fuel mixture for the power stroke.

■ Cooling systems. There are both air-cooled and liquid-cooled engines in use. Nearly all of today's engines have liquid-cooling systems.

■ Fuel type. Several types of fuel currently used in automobile engines include gasoline, natural gas, methanol, diesel, and propane. The most commonly used is gasoline although new fuels are being tested.

To find the correct specifications for an engine, a technician must know how to use the vehicle identification number (VIN). The VIN is a code of seventeen numbers and letters stamped on a metal tab that is riveted to the instrument panel close to the windshield. From this number much information about the vehicle can be found.

The adoption of the seventeen-number-and-letter code became mandatory beginning with 1981 vehicles. The standard VIN of the United Sates National Highway Transportation and Safety Administration Department of Transportation is being used by all manufacturers of vehicles, both domestic and foreign.

By referring to the VIN, much information about the vehicle can be determined. An engine serial number is also stamped on blocks. Its location is different for the different manufacturers. The service manual will tell you where to look for it. The engine code is generally found beside the serial number. A typical engine code might be DZ or MO. These letters indicate the horsepower rating of the engine, whether it was built for an automatic or manual transmission, and other important details. The engine code will help you determine the correct specifications for that particular engine.

Casting numbers are often mistaken for serial numbers and engine codes. Manufacturers use a casting number to identify major engine parts on the assemble line. They seldom can be used to identify the type of engine. Normally casting numbers are raised from the metal while ID numbers are usually stamped.

New Words

produce[prəˈdju:s] vt. 生产，制造

efficient[iˈfi∫ənt] adj. 有效率的

vehicle[ˈvi:ikl] n. 交通工具，车辆

manufacturer [ˌmænjuˈfækt∫ərə] n. 制造商，制造厂cylinder[ˈsilində] n. 汽缸

carburetor [ka:bəˈretər] n. 化油器

breaker[ˈbreikə] n. 断电器

point[pɔint] n. 触点

emission[iˈmi∫ən] n. 排放

fuel[fjuəl] n. 燃料，燃油

efficiency[iˈfi∫ənsi] n. 效率

monitor[ˈmɔnitə] vt. 监控

consume[kənˈsju:m] vt. 消耗

proportion[prəˈpɔ:∫ən] n. 比例

pollutant[pəˈlu:tənt] n. 污染物质

performance [pəˈfɔ:məns] n. 特性；性能

electronic[ilekˈtrɔnik] adj. 电子的

sensor [ˈsensə] n. 传感器

delivery[diˈlivəri] n. 传输，分配

ignition[igˈni∫ən] n. 点火，点燃

liter[ˈli:tə] n. 升（容积单位）

horsepower [ˈhɔ:sˌpauə] n. 马力，功率

automotive[ɔ:təˈməutiv] adj. 汽车的

technician[tekˈni∫(ə)n] n. 技术员，技师

stroke[strəuk] n. 冲程，行程

arrangement[əˈreindʒmənt] n. 排列

valve[vælv] n. 阀，气门

camshaft[ˈkæm∫a:ft] n. 凸轮轴

intake[ˈinteik] n. 吸入，进气

exhaust[igˈzɔ:st] n. 排气

ignition [igˈni∫ən] n. 点火，点燃

compression[kəmˈpre∫(ə)n] n. 浓缩，压缩

gasoline [ˈgæsəli:n] n. 汽油

cooling[ˈku:liŋ] n. 冷却

liquid[ˈlikwid] n. 液体，流体

methanol [ˈmeθənɔl] n. 甲醇

propane [ˈprəupein] n. 丙烷

specifications [ˌspesifiˈkei∫ən] n. 规范，规格，技术说明windshield [ˈwind∫i:ld] n. 挡风玻璃

manual[ˈmænjuəl] n. 手册，指南；adj. 手的，手动的

automatic[ˌɔ:təˈmætik] adj. 自动的

transmission [trænzˈmi∫ən] n. 变速器

Phrases and Expressions

eight-cylinder engine 8缸发动机

breaker point 断电器触点

electronic fuel injection system 电子燃油喷射系统

electronic ignition system 电子点火系统

fuel efficiency 燃油效率

harmful pollutant 有害污染物

computerized engine control system 计算机控制的发动机控制系统

ignition timing 点火正时

emission system 排气系统

engine support system 发动机供给系统

operational cycle 工作循环

valve train 配气机构

overhead camshaft (OHC) 顶置凸轮轴

exhaust valve 排气门

double overhead camshaft (DOHC) 双凸轮轴顶置

ignition system 点火系统

air-fuel mixture 空气-燃油混合气

compression ignition engine 压燃式发动机

spark plug 火花塞

power stroke 做功冲程

cooling system 冷却系

vehicle identification number (VIN) 车辆识别码

instrument panel 仪表盘

service manual 保养手册

engine code 发动机编码

Notes

1. In trying to produce more efficient vehicles, American manufacturers put four-cylinder and other small engines into their cars, instead of large eight-cylinder engines.为了生产更高效率的车辆，美国生产商将4缸和其他的小型发动机安装在了轿车上，而不采用8缸发动机了。

In trying to produce more efficient vehicles 动词的现在分词作目的状语。

instead of 代替，取代。例如：

Will you go to the party instead of me? 你替我赴宴好吗？

Shall we have fish instead of meat today? 今天我们不吃肉吃鱼好吗？

2. Fuel and air were carefully monitored and consumed in proportions that maximized the performance of the smaller engines while minimizing the production or harmful pollutants.燃油和空气被精确监测，并且消耗比例按照小型发动机能获得最高性能而产生最低有害排放物的混合比例进行燃烧。

in proportion 相称，符合比例。例如：

His features are in proportion. 他五官端正。

In drawing a person, it is difficult to get all the parts of the body in proportion.画人时，很难将身体各部分画得成比例。

3. They provide enough power to have these cars accelerate at nearly the same rate as (or quicker than) the larger-engined cars of the 1960s. 与20世纪60年代的装备大型发动机的小汽车相比，这些发动机提供了足够的功率使其驱动的汽车具有相同（或者更高）的加速性能。

at the same… 以同样的…。例如：

at the same rate 以同样的比率。

at the same speed 以同样的速度。

4. They also do this in cars that corner and stop very well. 它们的转向与制动也非常好。

that corner and stop very well 限制性定语从句修饰。

5. In recent years, the way horsepower is measured has changed. As a result, it seems as though today's engines are weaklings compared to those of yesterday. 近年来，发动机功率的测量方法已经发生变化，与以前的发动机相比，今天的发动机看起来像是功率降低了。

horsepower is measured 省略关系代词的限制性定语从句，修饰前面的way。

seem 似乎，好像。系动词，后接形容词或表语从句。

compared to those of yesterday 过去分词作比较状语。

6. 300 horsepower appears to be nothing compared to the 400+ horsepower that was available in the 1960s. 300马力看起来似乎无法和20世纪60年代所用的400多马力比较。

that was available in the 1960s 定语从句修饰前面的horsepower。

horsepower 马力（功率单位），通常简写为hp。

7. Not only are engine support systems controlled by computers, nearly every other major system on a car has some sort of electronic control. 不仅发动机系统由计算机控制，几乎汽车上的每个主要系统都由电子控制。

not only 置于句首必须引导倒装句，含义为“不仅…”例如：

Not only was Michael Jordan a basketball superstar he was part of great teams.迈克尔·乔丹不仅是一个篮球巨星，他还是伟大球队的一部分。

8. Most technicians will generally come in contact with only four-stroke engines.大多数技术人员接触到的仅有四冲程发动机

in contact with 与… 联系，接触。例如：

Finally he managed to get in contact with them.他终于设法与他们取得了联系。

In fact, we have it is in contact with the opponents gradually grew up. 其实，我们也正是在与对手的交往中逐步成长起来的。

9. By referring to the VIN, much information about the vehicle can be determined. 通过查阅VIN，关于车辆的很多信息都能被查到。

refer to 涉及，谈到，提到；关系到。例如：

He never referred to his sisters in his letters. 他在信里从未提到过他的姊妹。

10. Casting numbers are often mistaken for serial numbers and engine codes. 铸造号码经常与序列号和发动机编码弄混。

casting numbers 动名词短语作主语。

mistake vt. 误解，弄错。例如：

You must have mistaken my intentions. 你一定是误会了我的意图了。

be mistaken for 被误认为…，被误解为。例如：

Fertile lands in some states could be mistaken for lakes. 一些州中肥沃的土地可能会变为湖泊。

11. These letters indicate the horsepower rating of the engine, whether it was built for an automatic or manual transmission, and other important details. 这些字母表明发动机的功率等级，是否要与自动变速器或者手动变速器配合，和其他的重要细节。

be built for.. 为…而建造。例如：

A botanic garden will be built for us to visit and practice in. 将建一座植物园供我们参观和实践。

automatic transmission, AT 自动变速器

manual transmission, MT 手动变速器

Review Questions

1. In trying to produce more efficient vehicles, American manufacturers put ____ and other small engines into their cars, instead of large eight-cylinder engines.

2. Some basic engine systems like carburetors and ignition breaker points were replaced by electronic fuel injection and ____ systems.

3. After a prolonged period of economic growth in the 1980s, the demand for good ____ was once again a shaping force in automotive design.

4. What do the computerized engine control systems control?

5. In recent years, the way ____ is measured has changed.

6. Why does it seem today's engines are weaklings compared to those of yesterday?

7. How can we classify the today's automotive engines?

8. An engine can be ____,____, or ____. Other more complicated designs have also been used.

9. In a spark ignition system, the air-fuel mixture is ignited by an ____.

10. How does the diesel engine ignite the air-fuel mixture?

11. Several types of fuel currently used in automobile engines include ____, natural gas, methanol,____, and propane.

12. The VIN is a code of seventeen numbers and letters stamped on a metal tab that is riveted to the ____ close to the windshield.

译文

发动机介绍

为了生产更高效率的车辆，美国生产商将4缸和其他的小型发动机安装在了轿车上，而不采用8缸发动机了。一些基本的发动机系统，如化油器和点火断电器被电控燃油喷射系统和电子点火系统所取代。

到20世纪80年代中期，美国汽车已经可以通过计算机和其他电子装置对排放和燃油效率进行自动控制。燃油和空气被精确监测，并且消耗比例按照小型发动机能获得最高性能而产生最低有害排放物的混合比例进行燃烧。

20世纪80年代，很长的一段经济增长后，对高性能车辆的需求再一次推动汽车设计，目前，电子传感器被用来监测发动机的运转，计算机控制的发动机控制系统控制空气和燃油的分配、点火正时、排放系统的工作和许多其他相关的工作。其结果是发动机燃烧清洁、节油且具有强劲动力。新型的、高技术、高性能的发动机的代表有通用公司的北极星发动机和福特发动机公司的DOHC（Double Overhead Camshaft双凸轮轴顶置）4.6L发动机，这些发动机排量大约为260立方英寸（4.2L），输出功率为300马力左右。与20世纪60年代的装备大型发动机的小汽车相比，这些发动机提供了足够的功率使其驱动的汽车具有相同（或者更高）的加速性能。而具有这样性能的同时，它们单位燃油行驶的里程至少提高了4倍，它们的转向与制动也非常好。

近年来，发动机功率的测量方法已经发生变化，与以前的发动机相比，今天的发动机看起来像是功率降低了，300马力看起来似乎无法和20世纪60年代所用的400多马力比较，那样的想法是不对的，因为20世纪60年代400马力的发动机也就相当于与今天270马力的发动机。以前的发动机通过400多立方英寸（6.5L）的排量来产生那么多的功率，现在我们可以通过小很多的发动机来获得同样多的功率，区别在于总功率（旧）与有效功率（新）。

也许是计算机带来了汽车工业的重大变化。计算机不仅控制发动机供给系统，几乎汽车上每个主要系统都由电子控制。

如今的汽车发动机根据如下的设计特征可以分为：

■ 工作循环。大多数的技术人员接触到的仅有四冲程发动机，然而一些旧车使用过二冲程发动机，在将来的一些汽车也会使用。

■ 汽缸数目。当前的发动机设计有3缸、4缸、5缸、6缸、8缸、10缸和12缸的发动机。

■ 汽缸排列方式。一台发动机可以是水平的（对置）、直列的或者V型的，也采用其他更加复杂的结构。

■ 配气机构类型。发动机的配气机构可以是凸轮轴顶置（OHC）或者凸轮轴在缸体内的气门顶置（OHV）。有一些发动机进、排气门的凸轮轴是分开的，它们是基于OHC的设计，叫做双凸轮轴顶置发动机（DOHC），V型发动机的DOHC有四根凸轮轴——每侧两根。

■ 点火方式。有两种类型的点火系统：火花点燃式和压燃式。汽油机使用的是火花点燃系统。在火花点燃系统中，空气和燃料的混合物是被电火花点燃。柴油机或者压燃式发动机没有火花塞，柴油机依靠空气被压缩所产生的热量来为做功冲程点燃空气和燃料的混合物。

■ 冷却系统。发动机既有使用风冷的也有使用水冷的。现今几乎所有的发动机都采用水冷系统。

■ 燃料类型。现在有几种类型的燃料在汽车发动机上应用，包括汽油、天然气、甲醇、柴油和丙烷。尽管新型燃料正在测试，但是最常用的还是汽油。

为了查找到一台发动机正确的说明书，技术人员必须要知道如何使用车辆识别码（VIN）。VIN是一组刻在一块金属标签上的17位数字与字母，标签通过铆钉铆在接近挡风玻璃的仪表盘上。通过这个编码，我们可以得到关于车辆的很多信息。

从1981年生产的车辆开始，17位数字和字母编码开始强制采用。包括国内和国外的所有汽车生产厂商所使用的均为美国公路运输和运输安全管理部的标准VIN。

通过查阅VIN，关于车辆的很多信息都能被查到。发动机序列号也是被刻在缸体上的，不同的生产商所刻的位置也不相同，保养手册会告诉你在哪里查看。发动机编码一般在发动机序列号旁边，典型的发动机编码可能是DZ或者MO，这些字母表明发动机的功率等级，是否要与自动变速器或者手动变速器配合，和其他重要细节。发动机编码将帮助你确定具体发动机的正确规格。

铸造号码经常与序列号和发动机编码弄混。生产厂家利用铸造号码来确定组装线上主要发动机零件，它们很少能被用来确定发动机类型。铸造号码通常是在金属表面上突出的，而ID号码一般是刻上的。