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CHAPTER 1 AUTOMOTIVE BASICS
1.1 Principal Components
Today's average car contains more than 15,000 separate, individual parts that must work together. These parts can grouped into four major categories: engine, body, chassis and electrical equipment.
1.2 Engine
The engine acts as the power unit. The internal combustion engine is most common: this obtains its power by burning a liquid fuel inside the engine cylinder. There are two types of engine :gasoline(also called a spark-ignition engine) and diesel(also called a compression-ignition engine).Both engines are called heat engines; the burning fuel generates heat which causes the gas inside the cylinder to increase its pressure and supply power to rotate a shaft connected to the transmission.
1.3 Body
An automobile body is a sheet metal shell with windows, doors, a hood, and a trunk deck built into it. It provides a protective covering for the engine, passengers, and cargo. The body is designed to keep passengers safe and comfortable. The body styling provides an attractive, colorful, modern appearance for the vehicle.
1.4 Chassis
The chassis is an assembly of those systems that are the major operating part of a vehicle. The chassis includes the transmission, suspension, steering, and brake systems.
Transmission system s ― conveys the drive to the wheels. The main components are clutch, gearbox, driveshaft, final drive, and differential.
Suspension― absorbs the road shocks.
Steering― controls the direction of the movem ent.
Brake― slows down the vehicle.
1.5 Electrical Equipment
The electrical system supplies electricity for the ignition, horn, lights, heater, and starter. The electricity level is maintained by a charging circuit. This circuit consists of the battery, alternator (or generator). The battery stores electricity. The alternator changes the engine's mechanical energy into electrical energy and recharges the battery.
New Words
Principal component 主要部件
category 种类，类型
body 车身
chassis 底盘
layout 布置
power unit 动力装置
internal combustion engine 内燃机
cylinder 汽缸
gasoline 汽油
spark 火花
ignition 点燃，点火
diesel 柴油机
compression 压缩
shaft 轴
transmission 传动系
sheet metal 金属板
shell 外壳
hood （发动机）罩
trunk deck 行李舱盖
cargo 货物
styling 样式
assembly 总成，装配
suspension 悬挂，悬置
shock 冲击
steering 转向，操纵
brake 刹车，制动器
clutch 离合器
gearbox 变速器
driveshaft 传动轴
final drive 主减速器，后桥
differential 差速器
slow down （使）慢下来，减速
horn 喇叭
starter 起动机
charge 充电
alternator 交流发电机
Review Questions
1.List the main parts of an automobile?
2.What are the common types of a vehicle according to body styling?
3.Which systems does a chassis include and what are the main functions of the chassis?
4.Why are suspension systems used on vehicles?
CHAPTER2 INTERNAL COMBUSTION ENGINE
2.1 principle of operation
2.1.1 Engine and power
Engine is used to produce power. The chemical energy in fuel is converted to heat by the burning of the fuel at a controlled rate. This process is called combustion. If engine combustion occurs with the power chamber. ,the engine is called internal combustion engine. If combustion takes place outside the cylinder, the engine is called an external combustion engine.
Engine used in automobiles are internal combustion heat engines. Heat energy released in the combustion chamber raises the temperature of the combustion gases with the chamber. The
increase in gas temperature causes the pressure of the gases to increase. The pressure developed within the combustion chamber is applied to the head of a piston to produce a usable mechanical force, which is then converted into useful mechanical power.
2.1.2 Engine Terms
Linking the piston by a connecting rod to a crankshaft causes the gas to rotate the shaft through half a turn. The power stroke “uses up” the gas , so means must be provided to expel the burnt gas and recharge the cylinder with a fresh petrol-air mixture :this control of gas movement is the duty of the valves ;an inlet valve allows the new mixture to enter at the right time and an exhaust valve lets out the burnt gas after the gas has done its job. Engine terms are :
TDC(Top Dead Center):the position of the crank and piston when the piston is farther away from the crankshaft.
BDC(Bottom Dead Center):the position of the crank and piston when the piston is nearest to the crankshaft.
Stroke : the distance between BDC and TDC; stroke is controlled by the crankshaft.
Bore : the internal diameter of the cylinder.
Swept volume : the volume between TDC and BDC.
Engine capacity : this is the swept volume of all the cylinder e.g. a four-stroke having a capacity of two liters(2000cm) has a cylinder swept volume of 50cm.
Clearance volume: the volume of the space above the piston when it is at TDC. Compression ratio = (swept vol + clearance vol)\(clearance vol)
Two-stroke : a power stroke every revolution of the crank.
Four-stroke : a power stroke every other revolution of the crank..
2.1.3 The Four-stroke Spark-ignition Engine Cycle
The spark-ignition engine is an internal-combustion engine with externally supplied in ignition , which converts the energy contained in the fuel to kinetic energy.
The cycle of operations is spread over four piston strokes. To complete the full cycle it takes
two revolutions of the crankshaft. The operating strokes are :
This stroke introduces a mixture of atomized gasoline and air into the cylinder. The stroke starts when the piston moves downward from a position near the top of the cylinder. As the piston moves downward, a vacuum, or low-pressure area, is created.
During the intake stroke, one of the ports is opened by moving the inlet valve. The exhaust valve remains tightly closed.
Compression stroke
As the piston moves upward to compress the fuel mixture trapped in the cylinder, the valves are closed tightly. This compression action heats the air/fuel mixture slightly and confines it within a small area called the combustion chamber.
Power stroke
Just before the piston reaches the top of its compression stroke, an electrical spark is introduced from a spark plug screwed into the cylinder head.
The spark ignites the compressed, heated mixture of fuel and air in the combustion chamber to cause rapid burning. The burning fuel produces intense heat that causes rapid expansion of the gases compressed within the cylinder. This pressure forces the piston downward. The downward stroke turns the crankshaft with great force.
Exhaust stroke
Just before the bottom of the power stroke, the exhaust valve opens. This allows the piston, as it moves upward, to push the hot, burned gases out through the open exhaust valve. Then, just before the piston reaches its highest point, the exhaust valve closes and the inlet valve opens. As the piston reaches the highest point in the cylinder, known as TDC, it starts back down again. Thus, one cycle ends and another begins immediately.
2.1.4 Engine Overall Mechanics
The engine has hundreds of other parts . The major parts of engine are engine block , engine heads, pistons, connecting rods, crankshaft and valves. The other parts are joined to make systems. These systems are the fuel system, intake system, ignition system, cooling system, lubrication system and exhaust system. Each of these systems has a definite function. These systems will discussed in detail later.
NEW WORD
Piston 活塞
Connecting rod 连杆
Crankshaft 曲轴
Power stoke 活塞行程
Expel 排出
V alve 气阀
inlet(intake) valve 进气阀
exhaust valve 排气阀
term 术语
TDC 上止点
BDC 下止点
Bore 缸径
swept volume 有效容积
engine capacity 发动机排量
clearance volume 余隙容积,燃烧室容积
compression ratio 压缩比
revolution 旋转,转数
every other 每隔一个
cycle 循环
spread over 分布,遍及
intake stroke 进气行程
compression stroke 压缩行程
knock 敲缸,敲打
exhaust stroke 排气行程
engine block 发动机缸体
lubrication 润滑
2.2 Engine Block and Cylinder Head
2.2.1 Engine Block
The engine block is the basic frame of the engine. All other engine parts either fit inside it or fasten to it. It holds the cylinders, water jackets, and oil galleries. The engine block also holds the crankshaft, which fastens to the bottom of the block. The camshaft also fits inside the block, except on overhead-cam engines (OHC). In most cars, this block is made of gray iron, or an alloy (mixture) of gray iron and other metals, such as nickel or chromium. Engine blocks are castings.
Some engine blocks, especially those in smaller cars, are made of cast aluminum. This metal is much lighter than iron. However, iron wears better than aluminum. Therefore, the cylinders in most aluminum engines are lined with iron or steel sleeves. These sleeves are called cylinder sleeves. Some engine blocks are made entirely of aluminum.
2.2.2 Cylinder Head
The cylinder head fastens to the top of the block, just as a roof fits over a house. The underside forms the combustion chamber with the top of the piston. The most common cylinder head types are the hemi, wedge, and semi-hemi. All three of these terms refer to the shape of the engine's combustion chamber. The cylinder head carries the valves, valve springs and the rockers on the rocker shaft, this part of the valve gear being worked by the push-rods. Sometimes the camshaft is fitted directly into the cylinder head and operates on the valves without rockers. This is called an overhead camshaft arrangement. Like the cylinder block, the head is made from either cast iron or aluminum alloy.
2.2.3 Gasket
The cylinder head is attached to the block with high-tensile steel studs. The joint between the block and the head must be gas-tight so that none of the burning mixture can escape. This is achieved by using cylinder head gasket. This is a sandwich gasket, i.e. a sheet of asbestos between two sheets of copper, both these materials being able to withstand the high temperature and pressures within the engine.
2.2.4 Oil Pan or Sump
The oil pan is usually formed of pressed steel. The oil pan and the lower part of the cylinder block together are called the crankcase; they enclose, or encase, the crankshaft. The oil pump in the lubricating system draws oil from the oil pan and sends it to all working parts in the engine. The oil drains off and runs down into the pan. Thus, there is constant circulation of oil between the pan and the working parts of the engine.
New Words
engine block 缸体
cylinder head 气缸盖
fasten 使固定
water jacket 水套
oil gallery 油道
camshaft 凸轮轴
overhead-cam(OHC) 顶置凸轮
gray iron 灰铸铁
alloy 合金
nickel 镍
chromium 铬
casting 铸件
head cover 汽缸盖罩
intake manifold 进气总管
distributor 分电器
oil pan 油底壳
aluminum 铝
be lined with 镶有
cylinder sleeve 气缸套
hemi 半球形
wedge 楔型，楔入
semi-hemi 准半球形
rocker 摇臂
push-rod 推杆
gasket 衬垫
high-tensile 高强度的
stud 螺栓
gas-tight 密封的
asbestos 石棉
crankcase 曲轴箱，曲柄箱
encase 封闭，把…包起来
drain off 排出，流出
Review Question
1.What do TDC, BDC, stroke, compression ratio and engine capacity stand for?
2.How do you calculate swept volume and compression ratio?
3.What controls the length of the stroke?
4.List the main parts of the engine overall mechanics?
5.What are the main function of the engine block?
2.3 Piston Connecting Rod and Crankshaft
2.3.1 Piston Assembly
The piston is an important part of a four-stroke cycle engine. Most pistons are made from cast aluminum. The piston , through the connecting rod, transfers to the crankshaft the force create by the burning fuel mixture. This force turns the crankshaft .Thin, circular , steel bands fit into grooves around the piston to seal the bottom of the combustion chamber. These bands are called piston rings. The grooves into which they fit are called ring grooves. A piston pin fits into a round hole in the piston . The piston pin joins the piston to the connecting rod . The thick part of the piston that holds the piston is the pin boss.
The piston itself , its rings and the piston pin are together called the piston assembly.
2.3.2.Piston
To withstand the heat of the combustion chamber, the piston must be strong. It also must be light, since it travels at high speeds as it moves up and down inside the cylinder. The piston is hollow. It is thick at the top where it take the brunt of the heat and the expansion force. It is thin at the bottom, where there is less heat. The top part of the piston is the head , or crown . The thin part is the skirt The sections between the ring grooves are called ring lands.
The piston crown may be flat , concave ,dome or recessed . In diesel engine , the combustion chamber may be formed totally or in part in the piston crown , depending on the method of injection . So they use pistons with different shapes.
2.3.3Piston Rings
As Fig.2-9 shows , piston rings fit into ring grooves near the of the piston. In simplest terms, piston rings are thin, circular pieces of metal that fit into grooves in the tops of the pistons.
In modern engines ,each piston has three rings. (Piston in older engines sometimes had four rings, or even five.) The ring?s outside surface presses against the cylinder walls. Rings provide the needed seal between the piston and the cylinder walls. That is, only the rings contact the cylinder walls. The top two rings are to keep the gases in the cylinder and are called compression rings. The lower one prevents the oil splashed onto the cylinder bore from entering the combustion chamber , and is called an oil ring. Chrome-face cast-iron compression rings are commonly used in automobile engines. The chrome face provide a very smooth , wear-resistant surface.
During the power stoke , combustion pressure on the combustion rings is very high. It causes them to untwist . Some of the high-pressure gas gets in back of the rings. This force the ring face into full contact with the cylinder wall. The combustion pressure also holds the bottom of the ring tightly against the bottom of the ring groove. Therefore , high combustion pressure causes a tighter seal between the ring face and the cylinder wall.
2.3.4 Piston Pin
The piston pin holds together the piston and the connecting rod . This pin fits into the piston pin holes and into a hole in the top end of the connecting rod. The top end of is much smaller than the end that fits on the crankshaft . This small end fits
inside the bottom of the piston . The piston pin
fits through one side of the piston , through the
small end of the rod , and then through the other
side of the piston . It holds the rod firmly in place in
the center of the piston. Pins are made of
high-strengh steel and have a hollow center . Many
pins are chrome-plated to help them wear better.
2.3.3 Connecting rod
The connecting rod is made of forged high-strength
steel . It transmits and motion from the piston to the crankpin on the crankshaft . The connecting rod little end is connected to the piston pin . A bush made from a soft metal , such as bronze , is used for this joint . The lower end of the connecting rod fits the crankshaft journal . This is called the big end . For this big-end bearing , steel-backed lead or tin shell bearing are used . These are the same as those used for the main bearings . The split of the big end is sometimes at an angle , so that it is small enough to be withdrawn through the cylinder bore . The connecting rod is made from forged alloy steel .
2.3.5 Crankshaft
The crankshaft , in conjunction with the connecting rod , coverts the reciprocating motion of the piston to the rotary motion needed to drive the vehicle . It is usually made from carbon steel which is alloyed with a small proportion of nickel .The main bearing journals fit into the cylinder block and the big end journals align with the connecting rods .At the rear end of the crankshaft is attached the flywheel , and at the front end are the driving whells for the timing gears , fan , cooling water and alternator .
The throw of the crankshaft , the distance between the main journal and the big end centers , controls the length of the stroke . The stroke is double the throw , and the stroke-length is the distance that the piston travels from TDC to BDC and vice versa .
2.3.6 Flywheel
The flywheel is the made from carbon steel . It fit s onto the rear of the crankshaft . As well as keeping the engine rotating between power strokes it also carries the clutch , which transmits the drive to the transmission , and has the starter ring gear around its circumference . There is only one working stroke in four so a flywheel is needed to drive the crankshaft during the time that the engine is performing the non-power strokes .
New W ords Comprise 由。。。。。。。组成，包含
Inter 惯性，惯量
Radius 半径，范围
Circular 圆形的
Steel band 钢圈
Fit into 放入，放进
Groove 凹槽
Piston pin 活塞销
Pin boss 活塞销凸台
Withstand 抵抗
Hollow 空的
Brunt 冲力
Crown 活塞顶
Skirt 裙部
Ring land 环带
Concave 凹的，凹入的
Dome 圆顶
Recessed 隐蔽的
Cylinder wall 气缸壁
Cylinder bore 缸筒
Splash 飞溅
chrome-face 表面镀银的
Untwist 朝相反方向的
In place 在适当位置
Chrome-plated 镀铬的
Forge 伪造，仿造
Crankpin 曲轴销
Bush 轴瓦，套筒
Bronze 青铜
Crankshaft journal 曲轴轴颈
Steel-backed 钢背的
Lead 铅
Tin 锡
Splint 切口，中断，分配，分离
In conjunction with 连同
Reciprocating motion 往复运动
Rotary 旋转的
Carbon steel 碳钢
Journal 轴颈
Align with 匹配
Overlap 重叠
Timing gear 正时齿轮
Throw 摆幅
Vice verse 反之亦然
Impulse 脉冲
Space out 隔开，分隔
Through out 遍及
Diagram 图表
Firing order 点火顺序
Companion 成对
Circumference 圆周
2.4 Valve System
The valve system is made up of those parts needed to open and close the valves at just the right time .
2.4.1 Valve Operation
To coordinate the four-stroke cycle , a group parts called the valve train opens and closes the valves ( moves them down and up , respectively ) . These valve movements must take place at exactly the right moments . The opening of each valve is controlled by a camshaft .
1. Camshaft(OHC) Valve Train Overhead
The cam is an egg-shaped piece of metal on a shaft that rotates in coordination with the crankshaft . The metal shaft , called the camshaft , typically has individual cams for each valve in the engine . As the camshaft rotates , the lobe , or high spot of the cam , pushes against parts connected to the stem of the valve . This action forces the valve to move downward . This action could open an inlet valve , or open an exhaust valve for an exhaust stroke .
As the camshaft continues to rotate , the high spot moves away from the valve mechanism . As this occurs , valve spring pull the valve tightly closed against its opening , called the valve seat .
V alve in modern car engines are located in the cylinder head at the top the engine . This is known as an overhead valve (OHC) configuration . In addition , when the camshaft is located over the cylinder head , the arrangement is known as overhead camshaft (OHC) design . Some high-performance engine have two separate camshafts , one for each set of inlet and exhaust valves . These engines are known as overhead-camshaft (DHOC) engine .
2. Push-rod Valve Train
The camshaft also can be located in the lower part of the engine , within the engine block . To transfer the motion of the cam upward to the valve , additional parts are needs .
In this arrangement , the cam lobs push against round metal cylinders called follower
upward ( away from the camshaft ) . The cam follower rides against a push rod , which pushes against a rocker arm . The rocker arm pivots on a shaft through its center . As one side of the rocker arm moves up , the other side moves down , just like a seesaw . The downward-moving side of the rocker arm pushes on the valve stem to open the valve .
Because a push-rod valve train has additional parts , it is more difficult to run at high speeds . Push-rod engines typically run at slower speeds and , consequently , produce less horsepower than overhead-camshaft designs of equal size . ( Remember , power is the rate at which work is done .)
2.4.2 Valve Clearance
When the engine runs in compression stroke and power stroke , the valves must close tightly on their seats to produce a gas-tight seal and thus prevent the gases escaping from the combustion chamber . If the valves do not close fully the engine will not develop fill power . Also the valve heads will be liable to be brunt by the passing hot gases , and there is the likelihood of crown touching an open valve , which can seriously damage the engine .
So that the valves can close fully some clearance is needed in the operating mechanism . This means that the operating mechanism must be able to move sufficiently far enough away from the valve t allow the valves to be fully closed against its seat by the valve spring . However , if the clearance is set too great this will cause a light metallic taping noise .
2.4.3 Valve Timing
The time at which valves open and close ( valve timing ) and the duration of the valve opening in stated in degrees of crankshaft rotation . For example , the intake valve normally begins to open just before the piston has reached the top dead center . The valve remains open as the piston travels down to BDC and even past BDC . This is intake valve duration .An example of this could be stated as follows : IO at 17BTDC , IC at 51ABDC ( or , intake opens 17before top dead center , intake closes 51after bottom dead center ) . Intake valve duration in this case is 248 of crankshaft rotation .
This leaves 129 duration for the compression stroke since compression ends when the piston reaches TDC . At this point the power stroke begins . The power stroke ends when the exhaust valve begins to open approximately at 51 before bottom dead center . The duration of the power stroke in this case is also 129 .
Since the exhaust valve is opening at 51 BBDC , this begins the exhaust stroke . The exhaust stroke continues as the piston passes BDC and moves upward to past TDC . With the exhaust valve closing at 17 TTDC , the duration of the exhaust stroke is 248 .
It is apparent from this description that the exhaust valve stays open for a short period of time during which the intake valve is also open . In other words , the end of the exhaust stroke and the beginning of the intake stroke overlap for a short period of time . This is called valve overlap . V alve timing and valve overlap vary on different engines.
Opening the intake valve before TDC and closing it after BDC increase the fill of air-fuel mixture in the cylinder . Opening the intake valve early helps overcome the static inertia of the air-fuel mixture at the beginning of the intake stroke , while leaving the intake valve open after BDC takes advantage of the kentia of the moving air-fuel mixture . This increase volumetric efficiency .
As the piston moves down on the power stroke past the 90 A TDC position , pressure in the cylinder has dropped , and the leverage to the crankshaft has decreased due to connecting rod
angle and crankshaft position . This ends the effective length of the power stroke , and the exhaust valve can now be opened to begin expelling the burned gases . The exhaust valve remains open until the piston has moved up past the TDC position . This helps to remove as much of the burned gases as is possible and increase volumetric efficiency .
2.4.4 Cam Design and Control Dynamics
The function of the cam is to open and close the valves as far as possible , as fast as possible and as smoothly as possible . The closing force for the valves is applied by the valve spring which also maintain contact between the cam and the valves . Dynamic force impose limits on cam and valve lift .
The entire valve-train assembly can be view as a spring \mass system in which the conversion from stored to free energy causes force vibration . V alve-train assemblies with overhead camshafts can be represented with sufficient accuracy by a 1-mass system ( consisting of the moving mass , the valve-train assembly stiffness and corresponding damping ) .
For system with valve bottom-mounted camshaft and push rods , a 2-mass system is being increasingly used .
The maximum permissible contact stress , usually regarded as the parameter which limits cam-lobe radius and the rate of opening on the flank , currently lies between 600-700Mpa depending upon the material parings used .
2.4.5 Camshaft Drive Mechanism
Each cam must revolve once during the four-stroke cycle to open a valve. A cycle, remember, corresponds with two revolutions of the crankshaft . Therefore, the camshaft must revolve at exactly half the speed of the crankshaft . This is accomplished with a 2:1 gear ratio .A gear connected to the camshaft has twice the number of teeth as a gear connected to the crankshaft. The gears are linked in one of three ways:
1.Belt Drive
A cog-type belt can be used .Such belts are made of synthetic rubber and reinforced with
internal steel or fiberglass strands. The belts have teeth ,or slotted spaces to engage and drive teeth on gear wheels. A belt typically is used on engines with overhead-cam valve trains.
2.Chain Drive
On some engines, a metal chain is used to connect the crankshaft and camshaft gears. Most push-rod engines and some OHC engines have chains.
3.Gear Drive
The camshaft and crankshaft gears can be connected directly, or meshed. This type of operating linkage commonly is used on older six-cylinder, inline engines.
A camshaft driven by a chain or belt turns in the same direction as the crankshaft . But a
Camshaft driven directly by the crankshaft gear turns in the opposite direction. Timing belts are used because they cost less than chains and operate more quietly. A typical timing belt is made of neoprene (synthetic rubber) reinforced with fiberglass.
2.4.6 Electronic Valve Control System
An electronic value control (EVC) system replaces the mechanical camshaft, controlling each value with actuators for independent value timing. The EVC system controls the opening and closing time and lift amount of each intake and exhaust valve with independent actuators on each value. Changing from a mechanical camshaft driven value into
independently controlled actuator valves provides a huge amount of flexibility in engine control strategy. V ehicles utilizing EVC can realize several benefits including:
1)increases engine power and fuel economy,
2)allows centralized and distributed EVC systems to perform at their full potential,
3)adapts to engines of varied cylinder counts.
With all of the improved efficienc ies and consumer benefits, auto manufacturers are eager to get their first EVC systems on the road. The EVC system is targeted to operate in temperatures up to 125, while the actuator is targeted to run up to 6000 r/min. The actuator can be controlled in a centralized system with a high-speed multiplex bus (up to 10Mbps) or in a distributed system with a nominal speed bus.
EVC systems must be compact in size, specifically the actuators that must be small enough to fit in the engine space. A vehicle that uses a 42V system is ideal for EVC because it requires high voltage to control the value actuators, and EVC is targeted for V8 and V12 engines. The EVC system is also highly flexible, allowing adaptability for a number of cylinder engines.
New W ords
coordinate 协调
valve train 气阀传动
respectively 分别的，各自的
overhead camshaft 顶置凸微轮轴
guide 导管
tappet 挺杆
valve insert 气门座
cotter 锁销，锁片
opening 口
lobe 凸起
spot 点，位置
stem 杆
dual 双的
cam follower 凸轮挺杆
seesaw 跷跷板，杠杆
value clearance 气门间歇
gas-tight seal 气封
liable to 容易
likelihood 可能
tapping 轻敲
valve timing 配气正时
intake valve 进气阀
exhaust valve 排气阀
static 静态的，静力的
kinetic （运）动的，动力（学）的
volumetric 测定体积的
leverage 杠杆作用
offset 偏移量
dynamics 动力学
valve lift 气门挺杆
valve…as…把…..看成……
parameter 参数，参量
radius 半径，范围
flank 侧面
pairing 配对，成对
correspond with 相当于
gear ratio 传动比
cog-type belt 齿型带
synthetic rubber 合成橡胶
reinforce 加强
fiberglass 玻璃纤维
strand 绳，线，绞合
slotted 有槽的，切槽的
mesh 相啮合
linkage 联动
inline engine 直列发动机
neoprene 氯丁（二稀）橡胶
electronic valve control (EVC) 电子式气阀控制
centralized system 集中系统
distributed system 分布系统
varied cylinder count 可变的汽缸数
architecture 结构，构造
processor 处理器
local node 局域节点
communication layer 通信层
synchronization 同步
Review Question
1. List the main parts of the OHC valve train .
2. How does a push-rod valve train work ?
3. how are the valve clearance adjusted by hand ?
4. Why do the intake valves open before TDC and close after BDC ?
5. What do we mean by “ valve overlap “
6. Why do most cars use timing belts rather than chains ?
7. What are the advantage of the electronic valve control (EVC) ?
2.5 Gasoline Fuel System
2.5.1 Gasoline
Gasoline is distilled from crude petroleum . Gasoline is highly flammable , meaning it burns easily in the presence of air .
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 . V apor lock is common in fuel lines where the inlet side of the pump is exposed to high temperatures .
The flammability of gasoline varies with its quality and the additives mixed with the gasoline The way gasoline burns inside the combustion chamber is most important .
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 compression the fuel mixture to a smaller volume . Higher compression ratio not only boost power but also give more efficient power . But as the compression ratio goes up , knocking tendency increase . The octane number of a gasoline is a measure of its antiknock quality or ability to resist detonation during combustion . Detonation , sometimes referred to as knock , can be defined as an uncontrolled explosion of the last portion of the burning fuel-air mixture due to excessive temperature and pressure condition in the combustion chamber . Since detonation creates shock pressure waves , and hence audible knock , rather tan smooth combustion and expansion of the fuel-air mixture , it result in loss of power , excessive localized temperatures , and engine damage if sufficiently severe .
There are two commonly used methods of determining the octane number of motor gasoline the motor method and the research method . Both used the same type of laboratory single –cylinder engine , which is equipped with a variable head and a knock meter to indicate knock intensity . Using the test sample as fuel , the engine compression ratio and the air-fuel mixture are adjusted to develop a specified knock intensity . Two primary standard reference fuels , normal heptane and iso-octane , arbitrarily assigned 0 and 100 octane numbers , respectively , are then blended to produce the same knock intensity as the test sample . Thus , if the matching reference blend is made up of 15 n-heptane and 85 iso-octane , the test sample , the test sample is rate 85 motor or research octane number , according to the test method used .
2.5.2 Adaptation to Operating Condition
In certain operation conditions , the fuel requirement differs greatly from the basic injection-fuel quantity so that corrective is required in mixture formation .
1.Cold Start
During a cold start , the air-fuel mixture drawn in by the engine leans off . This is due to the low turbulence at cranking speeds causing poor mixture of the fuel particles with the air , and to the minimal evaporation of the fuel and wetting of the cylinder walls and intake ports with fuel at low temperature . In order to compensate for these phenomena , and thus facilitate staring of the cold engine , additional fuel must be injected during cranking .
2.Post-start Phase
After staring at low temperatures , it is necessary to enrich the mixture for a short period in order to compensate for poor mixture formation and wetting of the cylinder and intake-port walls with fuel . In addition , the rich mixture results in higher torque and therefore better throttle response when accelerating from idle .
3.W arm-up
The warm=up phase follows the cold-start and the post-start phase . The engine needs extra fuel during the warm-up phase because some of the fuel condenses on the still cold cylinder walls . At low temperatures , mixture formation is poor due to the large fuel droplets concerned , and due to the inefficient mixing of the fuel with the air drawn in by the engine , The result is that fuel condenses on the intake valves and in the intake manifold , and only evaporates at higher temperatures .
The above factors all necessitate an increasing enrichment of the mixture along with decreasing temperature .
4.Acceleration
If the throttle is opened abruptly , the air-fuel mixture is momentarily leaned-off , and a short period of mixture enrichment is needed to ensure good transitional response .
5 . Part Load
During part-load operation , achieving maximum air-fuel economy and observing the emission values are the crucial factors .
6.Full Load
The engine delivers maximum power at full load , when the air-fuel mixture must be enriched compared to that at part load .
This enrichment depends on engine speed and provide maximum possible torque over the entire engine-speed range . This also ensure optimum fuel-economy figures during full-load operation .
7.Idling
In addition to the efficiency of the engine , the engine idle speed principally determines the fuel consumption at idle .
The higher frictional resistances in the cold engine must be overcome by increasing the air-fuel mixture input . In order to achieve smoother running at idle , the idle-speed control increases the idle speed . This also leads to more rapid warm-up of the engine . Close-loop idle-speed control prevents too high an idle speed . The mixture quantity corresponds to the quantity required for maintaining the idle speed at the relevant load ( e.g.. cold engine and increased friction ) . It also permits constant exhaust-gas emission values for a long period without idle adjustment . Closed-loop idle-speed control also partially compensates for charges in the engine resulting from aging and ensures stable engine idling throughout the service life .
8.Overrun
Cutting off the fuel during deceleration reduces fuel consumption not merely on long downhill runs and during braking , but also in town traffic . Because no fuel is burnt , there are no emission .
9.Engine-speed Limiting
When a presser engine speed is reached , the ECU suppresses the fuel-injection pulses .
10.Adaptation of the Air-fuel Mixture at High Altitudes
The low density of air at high altitudes necessitates a leaner air-fuel mixture . At high altitudes , due to the lower air density , the volumetric floe measured by the air-fuel sensor corresponds to a lower air-mass floe . This error can compensated for by correcting the fuel quantity . Over-enrichment is avoided and , therefore , excessive fuel consumption .
2.5.3 Carburetor
As shown in Fig.2-20 , the fuel system has a fuel tank , fuel tank , fuel pump , fuel filter and carburetor . These parts store gasoline and deliver it to the carburetor as needed . Stated simply , the fuel tank stores the gasoline . The fuel lines carry the fuel from the tank to the carburetor . The fuel pump moves gasoline from the tank and through the fuel lines to carburetor . the fuel filter removes impurities from the gasoline . Then the carburetor sends the fuel ━a mixture of air and gasoline ━into the combustion chamber .
2.5.4 Motronic Combine Ignition and Fuel Injection System
The carburetor sends the correct air-fuel mixture to the engine . However , not all cars have carburetors . Fuel-injection systems are used on many modern cars .
Fuel-injection systems have many advantages over carburetors . For example , they provide more exact fuel control . Thus , they can better match air-fuel ratios to changing engine conditions . They also provide better economy and emission control . Furthermore , fuel-injection system do not need many of the parts that carburetor have .
The Motronic system is an engine-management system comprising a control unit ( ECU ) which implements at least the two basic function ignition and fuel injection , but which , however may contain additional subsystems as required for improves engine control .
1.Detection of Measured Valves
The combustion process in the cylinder is influenced not only by fuel management , mixture quantity and air-fuel ratio , but also by the ignition advance and the energy contained in the ignition spark . An optimized engine control the air-fuel ratio λthroughout the injection time t ( i.e. the quantity of injected fuel ) as well as the ignition advance angle αand the dwell angle β. The main parameters which effect the combustion process are detected as measure values and processed together such that the optimum ignition and injection timing is calculated for instantaneous engine operating conditions
2.Actuating Variables/Sensors
Engine speed and load are the main actuating variables . Because a specific ignition advance angle and a specific injection time correspond to each point of the engine speed/load map , it is important that all variables which pertain to the same point are calculate on the same speed /load area . This is only possible if the ignition advance and the injection time are calculated with the same speed and load valves ( engine speed detected only once with the same sensors ) .
This avoids statistical errors which can result , for example , from tolerances of different load sensor devices . Whereas a slightly different allocation in the part-load rage normally only increases consumption or exhaust emission , at full load near the knock limit the susceptibility t engine knocking increase . Clear allocation of the ignition timing angle and the injection time is provide by Motronic Systems , even under conditions of dynamic engine operation .
3.Motronic System
The Motonic system comprise a series of subsystem , the two basic subsystem being ignition and fuel injection . The combined system is more flexible and can implement a greater number of functions than the corresponding individual system . An important feature of the Motronic system is its implementation of a large number of freely programmable maps as desired for most sub-functions .
The exhaust gas recirculation (EGR) function has not been used in Europe to date , and is therefore provide only as an alternative systems . The lambda control system can only be considered today if used in conjunction with an adaptive precontrol for reasons of reduced exhaust emissions .
The knock control is either connected to the Motronic system via a defined interface , or integrated into the system . This combination of subsystem makes sense a physical standpoint : it enables a basic system ( ignition and fuel injection ) with open-loop functional control in a management system .
The idle speed control is realized by means of data from the ignition system and the fuel
汽车底盘构造习题解答 14—1、汽车传动系中为什么要装离合器？ （1）保证汽车平稳起步 切断和实现对传动系的动力传递，以保证汽车起步时将发动机与传动系平顺地结合，确保汽车平稳起步。 （2）保证换档时工作平稳 在换挡时将发动机与传动系分离，减少变速器中换挡齿轮之间的冲击。 （3）防止传动系过载 在工作中受到大的动载荷时，能限制传动系所受的最大转矩，防止传动系各零件因过载而损坏。 14—2、为何离合器从动部分的转动惯量要尽可能小？ 从动部分的转动惯量尽量小一些。这样，在离合器分离时能迅速中断动力传动；另外，在分离离合器换档时，与变速器输入轴相连部件的转速就比较容易减小，从而减轻换档时齿轮间的冲击。 14—3、为了使离合器接合柔和，常采用什么措施？ 在操作上要轻放离合器踏板；在结构上通常将从动盘径向切槽分割成扇形，沿周向翘曲成波浪形使其具有轴向弹性，接合柔和。 14—4、膜片弹簧离合器有何优缺点？ 优点：（1）弹簧压紧力在摩擦片允许磨损的范围内基本不变 （2）结构简单，轴向尺寸小，零件数目少 （3）操纵轻便，省力 （4）高速旋转时性能较稳定 （5）压力分布均匀，摩擦片磨损均匀 （6）散热通风好，使用寿命长 （7）平衡性好 （8）有利于批量生产，降低制造成本 缺点：制造工艺及尺寸精度要求严格使生产工艺复杂。 15—1、在普通变速器中，第二轴的前端为什么采用滚针轴承支承？为了润滑滚针轴承，在结构上都采取了哪些措施？ 因为一轴上的常啮合齿轮较小，支承孔较小，只能布置滚针轴承。且二轴上的斜齿轮主要产生轴向力，滚针轴承能承受较大的轴向力，可满足要求。在二轴的齿轮上钻有润滑油孔以润滑滚针轴承。 15—2、在变速器的同步器中，常把接合齿圈与常啮斜齿轮制成两体（二者通过花键齿连接），这是为什么？接合齿圈把由常啮斜齿轮传来的转矩传给接合套，但接合齿圈的
总论 一、填空题 1.世界上第一辆装有功率为 625 汽油机、最大车速为 15KM/H 的三轮汽车是由德国工 程师卡尔·奔驰于1885年在曼海姆城研制成功，1886年1月29日立案专利的。 因此人们把 1886 年称为汽车诞生年，卡尔·奔驰被称为“汽车之父”。 2.由于科学技术的发展，从第一辆汽车诞生至今，汽车的外形发生了巨大的变化，汽车的外 形就轿车而言有马车型、甲壳虫型、厢型、船型、楔型和鱼型，而楔形汽车已 接近于理想的汽车造型。 3.1889年法国的别儒研制成功了差速器和齿轮变速器；1891年摩擦片式离合器在法国 开发成功；1891年法国首先采用了前置发动机后轮驱动。 4.未来的汽车造型更趋于流线型，将有陆空两用优点的“空中公共汽车”；可在泥泞道路 或沼泽地自由行走的履带式气垫汽车；有仿动物行走特征的四“腿”无轮步行式汽车； 水陆空·三用汽车及飞碟汽车、潜艇式汽车。 5.我国汽车工业的建立是在1956年10月以第一汽车制造厂的建成投产为标志 的，从此结束了我国不能制造汽车的历史。1968年我国在湖北十堰市又开始建设了第二汽 车制造厂。它们的第一代产品分别是 CA10 型、 EQ140 型；第二代产品分别是CA141 型、 EQ140－1 型；第三代产品分别是 CA1092型、 EQ1092型。 6.按照国标GB3730.1－88《汽车和挂车的术语和定义》中规定的术语和汽车类型，汽车分 为轿车、载客车、载货车、牵引车、特种车、工矿自卸车和越野车等七类。 7.现代汽车的类型虽然很多，各类汽车的总体构造有所不同，但它们的基本组成大体都可分 为发动机、底盘、车身和电器用电子设备四大部分。 8.汽车从静止到开始运动和正常行驶过程中，都不可避免地受到外界的各种阻力。假定汽车 作等速直线行驶，这时汽车所受到的阻力有滚动阻力、空气阻力和坡度阻力。 二、解释术语 1.SX4225NT324 陕汽牵引汽车，汽车总质量22吨 2.整车装备质量 汽车完全装备好的质量，包括润滑油、燃料、随车工具、备胎等所有装置的质量。 3.最大装载质量 在汽车自身各零部件所允许的范围内，能保证汽车在道路上稳定行驶的汽车的最大的货物装 载量。即我们通常所说的载重。 4.转弯半径 指当方向盘转到极限位置时,外侧前轮轨迹圆半径。 5.平均燃料消耗量 汽车在道路上行驶时每百公里平均燃料消耗量。 6.记号（6×2）或（4×2）在表示驱动方式时的含义 六轮两驱、四轮两驱。 三、问答及论述题 1.汽车发动机的基本作用是什么？ 为车辆提供动力。 2.汽车底盘的含义是什么？其基本作用是什么？ 底盘是接受发动机的动力，是汽车运动并按驾驶员的而正确行驶的部件。
选择题 一、绪论 1、（）可减少零件的磨损。 A 增加零件的尺寸 B 增加零件的质量 C 增加零件的表面硬度 D 增加零件的刚度 2、疲劳断裂是材料在（）载荷作用下产生的一种破坏形式。 A 交变B弯曲C扭曲 D 冲击 3、发动机（）是指为维持发动机完好技术状况或工作能力而进行的作业。 A 修理B维护 C 保养 D 检测 4、发动机（）是指为恢复发动机完好技术状况或工作能力而进行的作业。 A 修理 B 维护 C 保养 D 检测 5、车辆维护应贯彻预防为主、（）维护的原则。 A 强制 B 定期 C 视情 D 定公里 6、车辆修理应贯彻预防为主、（）维护的原则。 A 强制 B 定期 C 视情 D 定公里 7、（）不是发动机作业的内容。 A 清洁 B 检查 C 紧固 D 拆装 8、修理尺寸法是指将零件磨损表面通过机械加工方法恢复其正确的（）并与相配合零件恢复配合性质的一种加工方法。 A 尺寸 B 几何形状C直径D半径 9、根据相对过盈的大小、镶套配合分为四级，镶气门座圈属于（）。 A轻级B中级C重级D特重级 10、根据相对过盈的大小、镶套配合分为四级，镶气缸属于（）。 A轻级B中级C重级D特重级 11、根据相对过盈的大小、镶套配合分为四级，镶气门导管属于（） A轻级B中级C重级D特重级 12、根据相对过盈的大小、镶套配合分为四级，镶飞轮齿圈属于（） A轻级B中级C重级D特重级 二、发动机总论 1、曲轴转二圈，活塞运动四个行程完成一个工作循环的发动机称为（）。 A 一冲程 B 二冲程C三冲程D四冲程 2、曲轴转一圈，活塞运动四个行程完成一个工作循环的发动机称为（）。 A 一冲程 B 二冲程C三冲程D四冲程 3、活塞处于下止点时活塞上方的容积称为（）。 A 燃烧室容积 B 气缸工作容积 C 气缸总容积 D 排量 4、活塞处于上止点时活塞上方的容积称为（）。 A 燃烧室容积 B 气缸工作容积 C 气缸总容积 D 排量 5、所有气缸工作容积之和称为发动机的（）。 A 燃烧室容积 B 气缸工作容积 C 气缸总容积 D 排量 6、压缩比等于气缸总容积与（）的比值。 A 燃烧室容积 B 气缸工作容积 C 气缸总容积 D 排量 7、汽油机的压缩比（）柴油机的压缩比。 A 大于 B 小于C等于 D 大于或等于 8、汽油机的最高燃烧温度（）柴油机的最高燃烧温度。 A 高于 B 低于C等于 D 低于或等于 9、汽油机的最高燃烧压力（）柴油机的最高燃烧压力。 A 高于 B 低于C等于 D 低于或等于 10在工作循环中，汽油机的进气终了压力（）大气压力。 A 高于 B 低于C等于 D 低于或等于 11在工作循环中，汽油机的排气终了压力（）大气压力。
汽车底盘构造课后习题解答14—1、汽车传动系中为什么要装离合器？ （1）保证汽车平稳起步 切断和实现对传动系的动力传递，以保证汽车起步时将发动机与传动系平顺地结合，确保汽车平稳起步。 （2）保证换档时工作平稳 在换挡时将发动机与传动系分离，减少变速器中换挡齿轮之间的冲击。 （3）防止传动系过载 在工作中受到大的动载荷时，能限制传动系所受的最大转矩，防止传动系各零件因过载而损坏。 14—2、为何离合器从动部分的转动惯量要尽可能小？ 从动部分的转动惯量尽量小一些。这样，在离合器分离时能迅速中断动力传动；另外，在分离离合器换档时，与变速器输入轴相连部件的转速就比较容易减小，从而减轻换档时齿轮间的冲击。 14—3、为了使离合器接合柔和，常采用什么措施？ 在操作上要轻放离合器踏板；在结构上通常将从动盘径向切槽分割成扇形，沿周向翘曲成波浪形使其具有轴向弹性，接合柔和。 14—4、膜片弹簧离合器有何优缺点？ 优点：（1）弹簧压紧力在摩擦片允许磨损的范围内基本不变 （2）结构简单，轴向尺寸小，零件数目少 （3）操纵轻便，省力 （4）高速旋转时性能较稳定 （5）压力分布均匀，摩擦片磨损均匀 （6）散热通风好，使用寿命长 （7）平衡性好 （8）有利于批量生产，降低制造成本 缺点：制造工艺及尺寸精度要求严格使生产工艺复杂。 15—1、在普通变速器中，第二轴的前端为什么采用滚针轴承支承？为了润滑滚针轴承，在结构上都采取了哪些措施？ 因为一轴上的常啮合齿轮较小，支承孔较小，只能布置滚针轴承。且二轴上的斜齿轮主要产生轴向力，滚针轴承能承受较大的轴向力，可满足要求。在二轴的齿轮上钻有润滑油孔以润滑滚针轴承。 15—2、在变速器的同步器中，常把接合齿圈与常啮斜齿轮制成两体（二者通过花键齿
汽车构造各章重点复习思考题解答 第九章发动机起动系统 9-2.车用起动机为什么采用串励直流电动机串励直流电动机由哪些基本部分组成 （作业）解答：由于串励直流电动机工作时，励磁电流与电枢电流相等，可以产生强大的电磁转矩，有利于发动机起动；同时它还具有低转速时产生的磁场大、电磁转矩随着转速的升高而减小的特性，使起动发动机时安全可靠。因此，被车用起动机广泛采用。串励直流电动机由电枢、磁极铁心、换向器、机壳和端盖等组成。（P312）9-3.起动机的传动机构有什么作用试说明滚柱式单向离合器的基本结构。（作业）（315~316页）解答：起动机的传动机构安装在电动机电枢的延长轴上，用来在起动发动机时，将驱动齿轮与电枢轴联成一体，使发动机起动。在发动机起动后，驱动齿轮的转速超过电枢轴的正常转速时，传动结构应使驱动齿轮与电枢轴自动脱开，防止电动机超速。滚柱式单向离合器由外座圈、内座圈、花键套筒、飞轮齿圈、滚柱、以及装在内座圈孔中的柱塞和弹簧等组成。 第十章汽车传动系统概述 10-2．汽车传动系统具有哪些功能各项功能是通过哪些部件来实现的(作业)（2~4页） 解答：（1）实现减速增矩，通过变速器和主减速器共同实现；（2）实现汽车变速，通常由变速器实现；（3）实现汽车倒驶，通过变速器中的倒挡机构实现；（4）必要时中断动力传递，通过离合器来实现；（5）使两侧驱动轮具有差速作用，由差速器实现；（6）实现变角度传递动力，由万向传动装置来实现。 第十一章离合器 11-1．汽车传动系统为什么要安装离合器（作业）（P11-12） 11-2.为何离合器的从动部分的转动惯量要尽可能的小 解答：离合器的功用之一是当变速器换挡时中断动力传递，以减少齿轮间冲击。如果与变速器主动轴相连的离合器从动部分的转动惯量大，当换挡时，虽然分离了离合器，使发动机与变速器之间的联系分开，但离合器从动部分较大的惯性力距仍然输送给变速器，其效果相当于分离不彻底，就不能很好的起到减轻齿轮间冲击的作
《汽车构造》教学设计 一、教学内容 1、课题：第三章配气机构 2、课型：新课 3、使用教材：中国劳动出版社出版周若柔主编全国技工学校汽车专业教材《汽车构造》 4、授课教师： 5、教学重点： （1）配气机构主要零部件的功用和结构特点； （2）配气相位和气门间隙的作用； （3）气门间隙的检查与调整； 6、教学难点： （1）配气相位分析； （2）气门间隙的两次调整法； 7、教学课时：2次课 二、教学对象分析 教学对象是汽车运用与维修专业二年级（0410班）学生，该班大部分学生学习积极性很高，对专业知识的求知欲很强，上课比较认真，在前面的实操训练中，每个同学都能认真操作，基本都能达到每个项目的实训要求。 三、教学目标 1、认知目标 （1）了解配气机构的功用和型式； （2）了解配气机构主要零部件的结构特点； （3）了解配气相位的概念； （4）了解气门间隙的作用和技术标准； 2、能力目标 （1）掌握气门间隙的检查与两次调整法； （2）掌握使用塞尺检查气门间隙的技巧； （3）掌握确定发动机第一缸活塞处于压缩行程上止点的方法； （4）掌握多缸发动机点火顺序的判别方法。 3、情感目标 （1）培养学生的动手操作能力和安全文明操作意识； （2）培养学生的团队协作能力； 四、教学方法 理论与实操相结合的一体化教学、模块化教学 五、教学过程和教学活动 （一）复习旧课 复习：发动机的工作原理（即进气、压缩、做功、排气四个行程） （二）导入新课 从发动机工作原理中的进、排气门开启和关闭现象引入配气机构的概念。
第三章配气机构 第一部分：理论讲解（60min） 1、配气机构概述（采用挂图教学，如图1所示） （1）配气机构的功用 （2）配气机构的结构型式 图1 2、配气机构的主要零部件（采用实物教学，如图2所示，重点讲解其结构特点） （1）气门组：包括气门、气门弹簧、气门导管、气门座、锁片等。 （2）气门传动组：包括凸轮轴、挺柱、推杆、揺臂等。 图2 图3 3、配气相位（采用挂图教学，如图3所示） （1）进气门的配气相位 （2）排气门的配气相位 （3）气门叠开 4、气门间隙（重点讲解） （1）气门间隙的概念与作用 提问：气门间隙过大或过小对发动机有什么影响？（学生回答） 教师总结
第一章：发动机的工作原理和基本构造 1上止点：活塞顶面离曲轴中心线最远时的止点。下止点：活塞顶面离曲轴中心线最近时的止点。 2活塞行程：活塞上下两个止点之间的距离。 3气缸工作容积：一个气缸中活塞运动一个行程所扫过的容积。 4发动机排量：一台发动机全部气缸的工作容积。 5压缩比：压缩前气缸中气体的最大容积与压缩后最小容积之比。6爆燃：气体压力和温度过高，在燃烧室内离点燃中心较远处的末端混合气自燃而造成的不正常燃烧。 7四冲程汽油机经过进气、压缩、燃烧作功、排气四个行程，完成一个工作循环。期间活塞在上下止点间往复移动了四个行程，曲轴旋转了两圈。 8四冲程发动机在一个工作循环的四个活塞行程中，只有一个行程是作功，另外三个为作功的辅助行程。（工作原理） 9汽油机的一般构造A机体组作用：作为发动机各机构、各系统的装配机体，而其本身的许多部分是其他机构的组成部分。B曲柄连杆机构：将活塞的直线往复运动变为曲轴的旋转运动并输出动力的机构。C配气机构作用：使可燃混合气及时冲入气缸并及时从气缸中排除废气。D供给系统作用：把汽油和空气混合成为成分合适的可燃混合气供入气缸，以供燃烧，并将燃烧生成的废气排出发动机。E 点火系统作用：保证按规定时刻点入气缸中被压缩的混合气。F冷却系统作用：把受热部件的热量散到大气中去，以保证发动机正常工作。G润滑系统作用：将润滑油供给作相对运动的零件，以减小他们之间的摩擦阻力，减轻部件的磨损并部分的冷却摩擦部件，清洗摩擦表面。H启动系统使静止的发动机启动并转入自行运转。 10有效转矩：发动机通过飞轮对外输出的平均转矩。 11有效功率：发动机通过飞轮对外输出的功率。 12发动机负荷：发动机驱动从动机械所耗费的功率或有效转矩的大小。 第二章：曲柄连杆机构 14曲柄连杆机构的功用：把燃气作用在活塞顶上的力矩转变为曲轴的转矩，以向工作机械输出机械能。 15曲柄连杆机构工作条件的特点：高温、高压、高速和化学腐蚀。16气缸体种类：一般是气缸体、龙门式气缸体、隧道式气缸体。
汽车构造英文版-免费下载版 CHAPTER 1 AUTOMOTIVE BASICS ? Principal Components Today's average car contains more than 15,000 separate, individual parts that must work together. These parts can grouped into four major categories: engine, body, chassis and electrical equipment. ? Engine The engine acts as the power unit. The internal combustion engine is most common: this obtains its power by burning a liquid fuel inside the engine cylinder. There are two types of engine :gasoline(also called a spark-ignition engine) and diesel(also called a compression-ignition engine).Both engines are called heat engines; the burning fuel generates heat which causes the gas inside the cylinder to increase its pressure and supply power to rotate a shaft connected to the transmission.
CHAPTER1AUTOMOTIVE BASICS 1.1Principal Components Today's average car contains more than15,000separate,individual parts that must work together.These parts can grouped into four major categories:engine,body,chassis and electrical equipment. 1.2Engine The engine acts as the power unit.The internal combustion engine is most common:this obtains its power by burning a liquid fuel inside the engine cylinder.There are two types of engine:gasoline(also called a spark-ignition engine)and diesel(also called a compression-ignition engine).Both engines are called heat engines;the burning fuel generates heat
which causes the gas inside the cylinder to increase its pressure and supply power to rotate a shaft connected to the transmission. 1.3Body An automobile body is a sheet metal shell with windows,doors,a hood,and a trunk deck built into it.It provides a protective covering for the engine,passengers,and cargo.The body is designed to keep passengers safe and comfortable.The body styling provides an attractive,colorful,modern appearance for the vehicle. 1.4Chassis The chassis is an assembly of those systems that are the major operating part of a vehicle. The chassis includes the transmission,suspension,steering,and brake systems. Transmission systems―conveys the drive to the wheels.The main components are clutch, gearbox,driveshaft,final drive,and differential. Suspension―absorbs the road shocks. Steering―controls the direction of the movement. Brake―slows down the vehicle. 1.5Electrical Equipment The electrical system supplies electricity for the ignition,horn,lights,heater,and starter. The electricity level is maintained by a charging circuit.This circuit consists of the battery, alternator(or generator).The battery stores electricity.The alternator changes the engine's mechanical energy into electrical energy and recharges the battery. New Words Principal component主要部件 category种类，类型 body车身 chassis底盘 layout布置 power unit动力装置 internal combustion engine内燃机 cylinder汽缸 gasoline汽油 spark火花 ignition点燃，点火 diesel柴油机 compression压缩
汽车构造上陈家瑞第3版复习资料 1、对于往复活塞式内燃机，曲轴每转两圈，活塞往复运动四次，完成进气、压缩、作功、排气一个工作循环 的称为四冲程内燃机。如果曲轴每转一圈，活塞往复运动两次，完成一个工作循环的称为二冲程内燃机。 2、气缸总容积（V a）等于气缸工作容积(V h)与燃烧室容积之和(V c)，即V a = V h+ V c 。 压缩比（ε）等于气缸总容积和燃烧室容积之比，ε= V a/ V c=( V h+ V c)/ V c=1+ V h/ V c 3、示功图：气缸内气体压力随曲轴转角或气缸容积变化的曲线图。（可用示功器在试验中直接测得的） 示功图的作用：由示功图可以得到许多重要数据，如气缸内气体的瞬时压力和温度，最高爆发压力，着火时刻，燃烧终点，燃烧规律等，它们是分析内燃机工作过程好坏的原始数据。 4、内燃机的总体构造，主要由以下几部分组成：机体、曲柄连杆机构、配气机构、燃油供给系、点火系、润滑系、冷却系、起动装置。 5、发动机主要性能指标：动力性能指标、经济性能指标、运行性能指标。 6、柴油机调速特性：在调速器起作用时，柴油机的性能指标随转速或负荷变化的关系。 有两级式调速器和全程式调速器两种。一般汽车上用二级式。工程机械、矿山机械等用柴油机一般装用全程式。（1）两级式调速器的调速特性：由于调速器的作用，使速度特性的两端得到调整。转速变化时，扭矩曲线急剧变化。中间部分按速度特性变化。 （2）全程式调速器：由于调速器的作用，柴油机的转矩和燃油消耗率曲线得到了改造，它不仅能限制超速和保持怠速稳定，而且能自动保持在选定的任何速度下稳定工作。 7、曲柄连杆机构受的力：主要有气压力P，往复惯性力P j，旋转离心力P c和摩擦力F。如图1。 注：只有在需要画分力时才需参照图2、图3、图4。 （1）气体压力P在每个工作循环的四个行程中始终存在。但进气行程和排气行程中气体压力较作功和压缩行程中的气体压力要小得多,对部件影响不大,故我们只讨论作功和压缩行程中的气体压力。 气压力P的集中力P P分解为侧压力N P和S P，S P分解为R P和T P，R P使曲轴主轴颈处受压，T P为周向产生转矩的力。①作功行程：侧压力N P向左，活塞的左侧面压向气缸壁，左侧磨损严重。如图2 ②压缩行程：侧压力N P向右，活塞的右侧面压向气缸壁，右侧磨损严重。T P对曲轴造成一个旋转阻力矩,企图阻止曲轴旋转。在压缩行程中,气体压力阻碍活塞向上运动。如图3 （2）往复惯性力P j：往复运动的物体,当运动速度变化时,产生往复惯性力。质量越大，转速越高，P j越大 ①当活塞从上止点向下止点运动时，其速度变化规律是：从零开始，逐渐增大，临近中间达到最大值，然后又逐渐减小至零。因为当活塞向下运动时，前半行程是加速运动。惯性力向上,后半行程是减速运动,惯性力向下。 ②相反，当活塞向上运动时，前半行程是加速运动。惯性力向下,后平行程是减速运动,惯性力向上。 （3）离心惯性力P C：方向总是背离曲轴中心向外。离心力在垂直方问的分力P Cy与往复惯性力P J方向总是一致的,加剧了发动机的上、下振动，水平方向的分力使发动机产生水平方向的振动。如图4 （4）摩擦力F：总与运动方向相反。它是造成配合表面磨损的根源。
— 汽车构造课后题答案 第二章机体组及曲柄连杆机构 1、为什么说多缸发动机机体承受拉、压、弯、扭等各种形式的机械负荷答：机体组是曲柄连杆机构、配气机构和发动机各系统主要零部件的装配基体。发动机工作时，各部件均在高速运动，有上下往复运动，摆动、旋转运动等。因此，对发动机产生不同形式的机械负荷。 2、无气缸套式机体有何利弊为什么许多轿车发动机都采用无气缸套式机体答：优点：可以缩短气缸中心距，从而使机体的尺寸和质量减少。机体的刚度大，工艺性好。 不足：为了保证气缸的耐磨性，整个铸铁机体需用耐磨的合金铸铁制造，这既浪费贵重材料，又提高制造的成本。 充分利用了无气缸套机体的优点。 ； 3、为什么要对汽油机气缸盖的鼻梁区和柴油机气缸盖的三角区加强冷却在结构上如何保证上述区域的良好冷却 答：这些部位如果冷却不良会导致汽油发生不正常燃烧，柴油机不正常过热，气缸盖开裂，进排气门座变形，漏气并最终损坏气门。 汽油机：气缸盖内铸出导流板，将来自机体的冷却液导向鼻梁区。 柴油机：气缸盖多采用分水管或分水孔形式，将冷却液直接喷向三角区。 4、曲柄连杆机构的功用如何有哪些主要零件组成 答：将活塞的往复运动转变为由曲轴的旋转运动，同时将作用在活塞上的力转变为曲轴对外输出的转矩，及驱动汽车车轮转动。 组成：活塞、活塞环、活塞鞘、连杆、连杆轴承、曲轴、飞轮。 5、为什么要把活塞的横断面制成椭圆形，而将其纵断面制成上小下大的锥形或桶形 ： 答：发动机在工作时，活塞有两种变形，①气体力和侧向力的作用下，发生机械变形，受热时发生热变形，使得在活塞销孔轴线方向的尺寸增大。为保证圆柱度，将活塞制成椭圆形，其长轴与活塞销孔轴线垂直。②活塞上的温度是在轴线方向上上高下低，其变形量是上大下小，因此，为使活塞工作的裙部接近圆柱形，须把活塞制成上小下大的圆锥形。 第三章配气机构 1、试比较凸轮轴下置式、中置式和上置式配气机构的优缺点及其各自的应用范围 答：优点： 下：凸轮轴离曲轴近，可以简单地用一对齿轮传动。 中：减少了传动机构的零件，减轻机构往复运动质量，增大了机构的刚度，适用了高转速发动机。 上：运动机件少，传动链短，整个机构刚度大，高速发动机。 缺点： " 下：零件多，传动链长，整个机构刚度差，高转速下可能破坏气门的运动规律和气门的定时启闭。 2、进、排气门为什么要早开晚关
第十三章汽车传动系概述 1、汽车传动系的基本功用是什么? 答: 汽车传动系的基本功用是将发动机发出的动力传给驱动车轮。 2、汽车传动系有几种类型?各有什么特点? 答:汽车传动系可分为机械式，液力机械式，静液式和电力式。机械式传动系的布置方案有前置前驱，前置后驱，后置后驱，中置后驱和四轮全驱，每种方案各有其优缺点。液力机械式传动系的特点是组合运用液力传动和机械传动。液力传动单指动液传动，即以液体为传动介质，利用液体在主动元件和从动元件之间循环流动过程中动能的变化来传递动力。静液式传动系又称容积式液压传动系，是通过液体传动介质的静压力能的变化来传动的。可以在不间断的情况下实现无级变速。但存在着机械效率低造价高使用寿命和可靠性不够理想等缺点。电力式传动系的优点是由于从发动机到车轮只由电器连接，可使汽车总体布置简化。此外它的无级变速性有助于提高平均车速，使操纵简化以及驱动平稳，冲击小，有利于延长车辆的使用寿命。缺点是质量大，效率低，消耗较多的有色金属-铜。 3、越野汽车传动系4*4与普通汽车传动系4*2相比，有哪些不同? 答:不同之处 1)前桥也是驱动桥。 2)在变速器与两驱动桥之间设置有分动器，并且相应增设了自分动器前驱动桥的万向传动装置。 3)在分动器与变速器之间，前驱动桥半轴与前驱动轮之间设有万向传动装置。 十四、传动系 1。汽车传动系统中为什么要装离合器？ 答：为了保证汽车的平稳起步，以及在换挡时平稳，同时限制承受的最大扭矩，防止传动系过载需要安装离合器。 2。为何离合器的从动部分的转动惯量要尽可能的小？ 答：离合器的功用之一是当变速器换挡时中断动力传递，以减少齿轮间冲击。如果与变速器主动轴相连的离合器从动部分的转动惯量大，当换挡时，虽然由于分离了离合器，使发动机与变速器之间的联系分开，但离合器从动部分较大的惯性力距仍然输送给变速器，其效果相当于分离不彻底，就不能很好的起到减轻齿轮间冲击的作用。所以，离合器的从动部分的转动惯量要尽量的小。 3。为了使离合器结合柔和，常采取什么措施？ 答：从动盘应有轴向弹力，使用扭转减震器。 4。膜片弹簧离合器有何优缺点？ 答：优点，膜片弹簧离合器的转距容量比螺旋弹簧要大15%左右，取消了分离杠杆装置，减少了这部分的摩擦损失，使踏板操纵力减小，且与摩擦片的接触良好，磨损均匀，摩擦片的使用寿命长，高速性能好，操作运转是冲击，噪声小等优点。 5。试以东风EQ1090E型汽车离合器为例，说明从动盘和扭转减震器的构造和作用？ 答：东风EQ1090E型汽车离合器从动盘是整体式弹性从动盘，在从动片上被径向切槽分割形成的扇形部分沿周向翘曲形成波浪形，两摩擦片分别与其波峰和波谷部分铆接，使得有一定的弹性。有的从动片是平面的，而在片上的每个扇形部分另铆上一个波形的扇状弹簧片摩擦片分别于从动片和波形片铆接。减震器上有六个矩形窗孔，在每个窗孔中装有一个减震弹簧，借以实现从动片于从动盘毂之间的圆周方向上的弹性联系。 其作用是避免传动系统共振，并缓和冲击，提高传动系统零件的寿命。 6。离合器的操纵机构有哪几种？各有何特点？ 答:离合器的操纵机构有人力式和气压式两类
CHAPTER 1 AUTOMOTIVE BASICS 第一章汽车原理 1.1 Principal Components 1.1 汽车主要组成部分 Today's average car contains more than 15,000 separate, individual parts that must work together. These parts can grouped into four major categories: engine, body, chassis and electrical equipment. 现代汽车有超过15000个零件组成，分成几个必须在一起工作的功能部分。主要包括4个功能部分：引擎，车身，底盘和电控。 1.2 Engine
1.2引擎 The engine acts as the power unit. The internal combustion engine is most common: this obtains its power by burning a liquid fuel inside the engine cylinder. There are two types of engine :gasoline(also called a spark-ignition engine) and diesel(also called a compression-ignition engine).Both engines are called heat engines; the burning fuel generates heat which causes the gas inside the cylinder to increase its pressure and supply power to rotate a shaft connected to the transmission. 引擎为汽车提供能源。一般是内燃机：通过在引擎缸内燃烧液体燃料获得能量。引擎有两种：汽油机和柴油机。两种引擎都叫热机。燃烧的燃料产生大量大热，热量使缸内的气体产生大的压力，通过连杆使曲轴旋转。 1.3 Body 1.3 车身 An automobile body is a sheet metal shell with windows, doors, a hood, and a trunk deck built into it. It provides a protective covering for the engine, passengers, and cargo. The body is designed to keep passengers safe and comfortable. The body styling provides an attractive, colorful, modern appearance for the vehicle. 车身有窗户，门，盖，内饰等组成，它为发动机，乘客及货物提供空间和保护。车身的设计要让乘客安全并乘坐舒适。对于乘用汽车，车身要动感，色彩绚丽，现代化。 1.4 Chassis 1.4 底盘 The chassis is an assembly of those systems that are the major operating part of a vehicle. The chassis includes the transmission, suspension, steering, and brake systems. 底盘是一个组合体，主要由汽车的操纵部分，传动系统，悬架，转向部分，制动系统组成。Transmission systems ― conveys the drive to the wheels. The main components are clutch, gearbox, driveshaft, final drive, and differential. 传动系统用来驱动车轮。主要有离合器，变速箱，驱动轴，最后驱动和差速器组成。 Suspension― absorbs the road shocks. 悬架主要用来吸收路面冲击。 Steering― controls the direction of the movement. 转向系统控制汽车的行驶方向。 Brake― slows down the vehicle. 制动系统使汽车停下来。 1.5 Electrical Equipment The electrical system supplies electricity for the ignition, horn, lights, heater, and starter. The electricity level is maintained by a charging circuit. This circuit consists of the battery, alternator (or generator). The battery stores electricity. The alternator changes the engine's mechanical energy into electrical energy and recharges the battery.
Today's average car contains more than 15,000 separate, individual parts that must work together . These parts can grouped into four major categories: engine, body, chassis and electrical equipment. 现代汽车有超过15000个零件组成，分成几个必须在一起工作的功能部分。主要包括4个功能部分：引 擎，车身，底盘和电控 。 Principal Components (汽车主要组成部分) 引擎
Engine 引擎 1、The engine acts as the power unit. 引擎为汽车提供能源。 2、 The internal combustion engine is most common: this obtains its power by burning a liquid fuel inside the engine cylinder . 一般是 内燃机：通过在引擎缸内燃烧液体燃料获得能量。 3、There are two types of engine :gasoline(also called a spark-ignition engine) and diesel(also called a compression-ignition engine). 引擎有两种： 汽油机和柴油机。 4、Both engines are called heat engines; the burning fuel generates heat which causes the gas inside the cylinder to increase its pressure and supply power to rotate a shaft connected to the transmission. 两种引擎都叫热机。燃烧的燃料产生大量大热，热量使缸内的气体产生大的压力，通过连杆使曲轴旋转。 Body 车身 An automobile body is a sheet metal shell with windows, doors, a hood, and a trunk deck built into it. It provides a protective covering for the engine, passengers, and cargo. The body is designed to keep passengers safe and comfortable. The body styling provides an attractive, colorful, modern appearance for the vehicle. 车身有窗户，门，盖，内饰等组成，它为发动机，乘客及货物提供空间和保护。车身的设计要让乘客安全并乘坐舒适。对于乘用汽车，车身要动感，色彩绚丽，现代化。 Chassis 底盘 The chassis is an assembly of those systems that are the major operating part of a vehicle. The chassis includes the transmission, suspension, steering, and brake systems. 底盘是一个组合体，主要由汽车的操纵部分，传动系统，悬架，转向部 分，制动系统组成。 1、Transmission systems ― conveys the drive to the wheels. The main components are 底盘 车身
★★比较重要的原理结构图：p365 4个图，p252 图,p285 图24-2，p307 图，p216 图p137 图18-27，p21 图，p50 图 缺少的地方：汽车产品型号（汽车构造上p12），★作业15-4，转向车轮定位参数的形成p174-176 名词解释： 1、万向传动装置：汽车传动系统中，在轴间夹角和轴的相互位置经常发生变化的转轴之间继续传递动力的装置。 2、承载式车身：以车身起车架的作用,将所有部件固定在车身上,所有的力也由车身来承受。 3、车桥(也称车轴)：通过悬架和车架(或承载式车身)相连，两端安装车轮，用来传递车架与车轮之间的各个方向的 作用力及力矩的装置。 4、转向系：用来改变或恢复汽车行驶方向的专设机构。 转向系的类型根据其转向能源的不同，可以分为机械转向系和动力转向系 5、悬架：车架(或承载式车身)与车桥(或车轮)之间的一切传力连接装置的总称。 6、汽车制动：使行驶中的汽车减速或停车，使下坡行驶的汽车的速度保持稳定，使已停驶的汽车保持不动。 7、制动系和制动力：汽车上装设一系列专门装置，驾驶员能根据道路和交通等情况，使外界(主要是路面)在汽车 某些部分(主要是车轮)施加一定的力，对汽车进行一定程度的强制制动。这种可控制的对汽车进行制动的外力,称为制动力。这样的一系列专门装置即称为制动系。 8、制动器：制动系中用以产生阻碍车辆的运动或运动趋势的力的部件。（分鼓式制动器和盘式制动器两类。） 9、定钳盘式制动器：制动钳体固定安装在车桥上，制动时两侧的制动块压向制动盘产生制动的钳盘式制动器。 10、整车整备质量：汽车完全装备好的质量，包括润滑油、燃料、随车工具、备胎等所有装置的质量。 1、传动系的组成（按动力传动顺序）：离合器、变速器、万向传动装置、驱动桥。其中万向传动装置由万向节和传动轴组成，驱动桥由主减速器、差速器和半轴组成。 传动系的功能：减速增矩、变速、实现汽车倒驶、必要时中断传动、差速作用、万向传动 2、汽车传动系统中为什么要装离合器？ 为了保证汽车平稳起步，以及在换挡时平顺，同时限制承受的最大扭矩，防止传动系过载，故需要安装离合器。3、摩擦式离合器工作原理：汽车在行驶过程中需经常保持动力传递, 中断传动只是暂时的需要。汽车离合器的主动部分和从动部分应经常处于接合状态。使离合器分离时,只要踩下离合器操纵机构中的踏板,套在从动盘毂环槽中的拨叉,推动从动盘克服压紧弹簧的压力向右移动而与飞轮分离,摩擦力消失,从而中断了动力传递。当需要重新恢复动力传递时，使离合器踏板慢慢回升，从动盘在压紧弹簧的压力作用下，向左移动与飞轮恢复接触，二者接触面间的压力逐渐增加、摩擦力矩也逐渐增加。 ★4、膜片弹簧离合器的组成（p21 图14-8）：飞轮、从动盘压盘、分离轴承、膜片弹簧、离合器盖等 工作原理（p22 图14-9）：当结合时，由于离合器盖靠向飞轮，膜片弹簧钢丝支承圈则压向膜片弹簧使之产生弹性变形，膜片弹簧的圆锥底角变小，几乎接近压平状态。同时，在膜片弹簧的大端对压盘产生压紧力，使离合器处于结合状态。当分离离合器时，分离轴承左移，膜片弹簧被压紧在前钢丝支承圈上，膜片弹簧变成反锥形状，使弹簧大端右移，并通过分离弹簧钩拉动压盘使离合器分离。 5、变速器功用：1）改变汽车的行驶速度和牵引力；2）改变驱动轮的旋转方向；3）使动力与驱动轮脱离；4）驱动其他机构。 6、变速器的变速传动机构：变速器由第一轴、中间轴、第二轴、倒档轴、壳体及变速器操纵机构等组成。 7、画变速器传动简图时，右图中齿 数Z1、Z2、等不用标出，箭头也不 用标出，图中箭头表示的是二档时的 传动路线。 第一轴为输入轴，第二轴为输出轴。 四档齿轮、三档齿轮和二档齿轮分 别通过各自的两排滚针轴承支承在 第二轴上。倒档齿轮制成一体,共同 通过两排滚针轴承支承在倒档轴。 传动比i=从动齿轮齿数/主动齿轮 齿数 如