車專業(yè)英語Unit-3-Passage-B課件

1、Unit Three Engine Systems Passage BIgnition, Starting and Fuel SystemsIgnition systemIgnition system is the most important part of the gasoline engine Its purpose is to ignite the compressed fuel-air mixture at proper time, producing power to move the car A good ignition system has a great impact on

2、 the engine performance, fuel economy and exhaust pollutionIgnition system is divided into 3 types: contact-point ignition system (Fig.3-15), non-point ignition system (Fig.3-16) and non-distributor ignition system ( Fig.3-17) First one is convention ignition system (CIS), the last two ones are elec

3、tronic ignition system (EIS). In non-point ignition system, a reluctor disk and an electronic control module (ECM) take the place of the contact points in the contact-point ignition systemWith the development of the automotive technology, non-distributor ignition system is replacing the other two ty

4、pes of the ignition systems mentioned above So we mainly introduce the non-distributor ignition systemThe major components of a non-distributor ignition system are engine control unit (ECU), ignition control unit (ICU), a set of ignition coils and some sensors such as crankshaft position sensor, cam

5、shaft position sensor and knock sensorThe spark plugs are fired directly from the coils The spark timing is controlled by ECU and ICU according to the information received from the sensors There are multiple coils on cars so each one serves one or two spark plugsIf there are 3 coils that mounted tog

6、ether in a coil pack in a car with a 6-cylinder engine, each coil is connected to two spark plugs with spark plug wires The coil fires bothspark plugs at the same time One spark plug fires on the compression stroke igniting the fuel-air mixture to produce power while the other spark plug fires on th

7、e exhaust stroke and does nothing (see Fig.3-17a).If there are 4 coils, each coil is mounted directly on the top of each spark plugas shown in 3-17b This design completely eliminates the spark plug wires for even better reliabilityStarting systemStarting system functions to crank the engine fast eno

8、ugh to allow the engine to start (see Fig.3-18). The starting system and ignition system must work together for good engine starting This system includes the following main components:Battery serves as an electrical energy source It produces electric current for starting the car, powering the igniti

9、on system and turning on the lights The battery converts electrical energy into chemical energy during charging and then converts it back into electricity during dischargingIgnition switch, also called key switch, controls the ignition circuit, starting system and the power for the car instrumentsSt

10、arter is a very powerful direct-current electric motor designed to crank the engine The starter has a small pinion gear which meshes with the ring gear on the flywheel When the driver turns the key switch, the starter drives the pinion gear, which, in turn, drives the flywheel and cranks the engineS

11、olenoid is mounted on the top of the starter It has two important functions: it controls the electrical circuit between the battery and starter; it shifts the pinion in and out of mesh with the ring gear (see Fig.3-19).Fuelsupply systemThe purposes of the fuel supply system are to supply the right a

12、mount of fuel for the engine to burn, and control the speed of the engine Lets look at the major parts of the fuel system as shown in Fig.3-20.Fuel tank (see Fig.3-21) is the energy storage for the engine. All cars have a single tank located in the rear of the cars In the tank there is a sending uni

13、t which tells the fuel gauge how much fuel is left in the tankFuel pump (see Fig.3-22) is usually located inside the fuel tank so as to keep the pump cool and quiet Nowdays, a fuel injected car uses an electric pump. Its purposes are to draw the fuel from the fuel tank and deliver it to the fuel sys

14、temFuel line uses steel lines and flexible hoses that carry the fuel from the tank to the engineFuel filter (see Fig.3-23) has an important job that removes dirt, rust and water from the fuel before it can reach the injection system.Fuel injector (see Fig.3-24) is nothing but an electronically contr

15、olled valve The function of the fuel injector is to deliver finely atomized fuel under high pressure to the combustion chamber of the engine.New Words and Expressionsperformance pfmns n 性能replace ripleis vt 取代, 代替sensor sens n 傳感器multiple mltipl adj 多個(gè)的eliminate ilimineit vt 淘汰reliability rilaibilti

16、 n 可靠性charging tdi n 充電discharging dista: di n 放電crank krk vt 起動flexible fleksibl adj 有彈性的injection indekn n 噴射atomized tmaizd adj 霧化的haveimpact on對影響engine performance發(fā)動機(jī)性能exhaust pollution排氣污染spark timing點(diǎn)火正時(shí)electric current電流electrical energy電能chemical energy化學(xué)能Common Automobile Termsbattery btri

17、 n 蓄電池starter stt n 起動機(jī)solenoid sulnid n 電磁開關(guān)pinion pinjn n 小齒輪; 驅(qū)動齒輪starting system起動系統(tǒng)fuelsupply system燃油供給系統(tǒng)contact-point ignition system觸點(diǎn)式點(diǎn)火系統(tǒng)non-point ignition system無觸點(diǎn)點(diǎn)火系統(tǒng)non-distributor ignition system無分電器點(diǎn)火系統(tǒng)conventional ignition system (CIS) 傳統(tǒng)點(diǎn)火系統(tǒng)electronic ignition system (EIS) 電子點(diǎn)火系統(tǒng)reluctor disk磁阻盤electronic control module (ECM) 電子控制模塊engine control unit (ECU) 發(fā)動機(jī)控制單元ignition