汽车专业英语 (2.5)

1、 Automotive engineering English2.1 Principle of Operation2.2 Engine Block and Cylinder Head2.3 Piston, Connecting Rod and Crankshaft2.4 Engine and Transmission Mounting2.5 Valve System2.1 工作原理2.2 发动机体和气缸盖2.3 活塞、连杆和曲轴2.4 发动机和变速器组件2.5 气阀系统Chapter 2 Internal Combustion Engine Automotive engineering Eng

2、lish2.6 Gasoline Fuel System2.7 Diesel Engine2.8 Engine Cooling2.9 Engine Lubrication2.10 Emission2.6 汽油燃料系统2.7 柴油发动机2.8 发动机的冷却2.9 发动机的润滑2.10 排放第二章第二章 内燃机内燃机 Automotive engineering EnglishChapter 2 Internal Combustion Engine Automotive engineering English2.4 Engine and Transmission Mountings2.4.1 In

3、herent Engine Vibrations2.4.2 Reasons for Flexible Mounting2.4.3 Axis of Oscillation2.4.4 Six Modes of Freedom of Suspended BodyChapter 2 Internal Combustion Engine Automotive engineering English2.5 valve systemChapter 2 Internal Combustion Engine Automotive engineering English2.5.1 Valve operation:

4、 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. (P26)凸轮是一个蛋形的金属块，它安装在同曲轴协调运转的一根金属轴上，该轴称为凸轮轴，其上有同发动机每一个气门对应的凸轮。Chapter 2 Internal Combustion Engine A

5、utomotive engineering English 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 for an intake stroke, or open an exhaust valve for an exhaust stroke

6、.(P26)当凸轮轴旋转时，凸轮的最高点，也就是凸圆，推动连接气门杆的部件，使得气门向下运动，在进气冲程打开进气门，在排气冲程打开排气门。Chapter 2 Internal Combustion Engine Automotive engineering English In this arrangement, the cam lobes push gainstround metal cylinders called cam follower. As the lobe of the cam comes up under the camfollower, it pushes the cam f

7、ollower upward(away from the camshaft). (P27)在这种方案中，凸轮基圆推动圆形的金属筒，也就是挺柱。凸轮凸圆运动到挺柱下方时，推动挺柱远离凸轮轴向上运动。Chapter 2 Internal Combustion Engine Automotive engineering English 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

8、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. （P27）挺柱带着推杆,推杆推动摇臂，摇臂绕摇臂轴的中心转动。摇臂的一端升起，另一端就落下，这类似于跷跷板。摇臂向下运动的一端推动气Chapter 2 Internal Combustion Engine Automotive engineering Eng

9、lish2.5.2 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 full power.(P2

10、8)当发动机在压缩冲程和作功冲程工作时，气门必须紧贴在气门座上，形成良好的气密性以防止燃烧室漏气。如果气门关闭不严，发动机就不能发挥出全部的功率。Chapter 2 Internal Combustion Engine Automotive engineering English Also the valve heads will be liable to be burnt by the passing hot gases, and there is the likelihood of the piston crown touching an open valve, which can ser

11、iously damage the engine.(P28)而且气门头部容易被经过的高温气体烧蚀，活塞顶部也可能会碰到气门使发动机严重损坏。Chapter 2 Internal Combustion Engine Automotive engineering English So that the valves can close fully someclearance is needed in the operating mechanism. This means that the operating mechanism must be able to move sufficiently f

12、ar enough away from the valve to allow the valves to be fully closed against its seat by the valve spring. (P28)所以在气门传动机构中要预留一些间隙使气门得以完全关闭。这就是说，气门传动机构运动要与气门有一个充分远的距离，使得气门在气门弹簧作用下紧闭气门座。Chapter 2 Internal Combustion Engine Automotive engineering English However, if the clearance is set too great this

13、will cause a light metallic tapping noise.(P28)可是如果间隙过大，会引起轻微的金属敲打声。Chapter 2 Internal Combustion Engine Automotive engineering English2.5.3 Valve timing: Basic wordsABDC:BBDC:ATDC:BTDC:IO:IC:EO:EC:Chapter 2 Internal Combustion Engine Automotive engineering English2.5.3 Valve timing: The time at whi

14、ch valves open and close (valve timing) and duration of valve opening is stated in degrees of crankshaft rotation. For example, the intake valve normally begins to open just before the piston has reached top dead center. 气门打开与关闭的时间及气门开启的时长可用曲轴转动的气门打开与关闭的时间及气门开启的时长可用曲轴转动的角度来表示。如进气门恰在活塞达到上止点前正常地开始打角度来

15、表示。如进气门恰在活塞达到上止点前正常地开始打开。开。 Chapter 2 Internal Combustion Engine Automotive engineering English 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 51 ABDC. Intake valve duration

16、 in this case is 248of crankshaft rotation. 气门在活塞向下运行到下止点甚至超过下止点时仍保持打开气门在活塞向下运行到下止点甚至超过下止点时仍保持打开。这是进气门打开的时长。这个例子可以这样说：进气在上止。这是进气门打开的时长。这个例子可以这样说：进气在上止点前点前17打开，在下止点后打开，在下止点后51关闭。进气门的开启时长为曲关闭。进气门的开启时长为曲轴转过轴转过248。Chapter 2 Internal Combustion Engine Automotive engineering English This leaves 129duratio

17、n for the compression stroke since compression ends when piston reaches TDC. At this point the power stroke begins. The power stroke ends when the exhaust valve begins to open approximately at 51BBDC.The duration of the power stroke in this case is also 129 . Chapter 2 Internal Combustion Engine Aut

18、omotive engineering English Since the exhaust valve is opening at 51BBDC, this begins the exhaust stroke. The exhaust stroke continues as the piston passes BDC and moves upward to and past TDC. With the exhaust valve closing at 17ATDC, the duration of the exhaust stroke is 248。Chapter 2 Internal Com

19、bustion Engine Automotive engineering English 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.由上显而易见，排气门在进气门打开的一小段时间内也打开着。Chapter 2 Internal Combustion Engine Automotive engineering English In other words, t

20、he end of the exhaust strokeand the beginning of the intake stoke overlap for a short period of time. This is called valve overlap. Valve timing and valve overlap vary on different engines.换句话说，排气冲程终了和进气冲程初期有一小段时间的重叠，这称为气门重叠。不同的发动机，其配气正时和气门重叠是不一样的。Chapter 2 Internal Combustion Engine Automotive engi

21、neering English Opening the intake valve before TDC and closing it after BDC increases the fill of air-fuel mixture in the cylinder. 在上止点前打开进气门和在下止点后关闭进气门可增加气缸内可燃混合气的进气量。Chapter 2 Internal Combustion Engine Automotive engineering English Opening the intake valve early helps overcome the static inert

22、ia of the air-fuel mixture at the beginning of the intake stroke, while leaving the intake valve open after BDC takes advantage of the kinetic inertia of the moving air-fuel mixture. This increases volumetric efficiency.提前打开进气门有助于克服进气冲程初期的惯性，同时在下止点后打开进气门可充分利用可燃混合气运动时的惯性，这可增加容积效率。Chapter 2 Internal C

23、ombustion Engine Automotive engineering English2.5.4 Cam design and control dynamic: 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 springs which also maintain conta

24、ct between the cam and the valves. Dynamic forces impose limits on cam and valve lift.Chapter 2 Internal Combustion Engine Automotive engineering English The entire valve-train assembly can be viewed as a spring/mass system in which the conversion from stored to free energy causes forced vibration.

25、整个气门机构可看成一个弹簧-质量系统，其储存的能量转化为自由能量时会引起受迫振动。Chapter 2 Internal Combustion Engine Automotive engineering English Valve-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 correspond

26、ing damping).带有顶置凸轮轴的气门机构可非常精确地用单质量系统来表示，由运动质量、气门机构的刚度和相应的阻尼组成。Chapter 2 Internal Combustion Engine Automotive engineering English2.5.5 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 cranksh

27、aft. Therefore, the camshaft must revolve at exactly half the speed of the crankshaft. 在一个四冲程的循环里，每个凸轮转动一次来打开一个气门。在一个循环里曲轴是转动两圈的。因此，凸轮轴正好以曲轴转速的一半旋转.Chapter 2 Internal Combustion Engine Automotive engineering English This is accomplished with a 2:1gear ratio. A gear connected to the camshaft has twic

28、e the Number of teeth as a gear connected to the crankshaft. The gears are linked in one of three ways.这是由2:1的传动比来实现的。连接凸轮轴的齿轮齿数是连接曲轴的齿轮齿数的两倍。齿轮的连接方式有三种。Chapter 2 Internal Combustion Engine Automotive engineering English Chapter 2 Internal Combustion Engine Automotive engineering English1.Belt Drive

29、（带驱动） 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.Chapter 2 Internal

30、 Combustion Engine Automotive engineering English 2.Chain Drive（链驱动） 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.Chapter 2 Internal Combustion Engine Automotive engineering English 3.Gear Drive（齿轮驱动） The

31、camshaft and crankshaft gears can be connected directly, or meshed. This type of operating linkage commonly is used on older six-cylinder, inline engines.Chapter 2 Internal Combustion Engine Automotive engineering English A camshaft driven by a chain or belt turns in the same direction as the cranks

32、haft. 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. Chapter 2 Internal Combustion Engin

33、e Automotive engineering English2.5.6 Electronic Valve Control System An electronic valve control system replaces the mechanical camshaft, controlling each valve with actuators for independent valve timing. The EVC system controls the opening and closing time and lift amount of each intake and exhau

34、st valve with independent actuators on each valve.电控气门系统代替机械式的凸轮轴，用执行器控制每个气门独立的进、排气正时。EVC通过每个气门上的独立执行器控制进气门和排气门的开启、关闭时间以及升程量.Chapter 2 Internal Combustion Engine Automotive engineering English Changing from a mechanical driven valve into independently controlled actuator valve provides a huge amount

35、 of flexibility in engine control strategy.由机械式驱动气门到独立控制执行器的气门改变给发动机控制策略提供了很大的灵活性。Chapter 2 Internal Combustion Engine Automotive engineering English Vehicles utilizing EVC can realize several benefits including: 1) increases engine power and fuel economy, 2) allows centralized and distributed EVC s

36、ystems to perform at their full potential, 3) adapts to engines of varied cylinder counts. Chapter 2 Internal Combustion Engine Automotive engineering English With all of the improved efficiencies and consumer benefits, auto manufacturers are eager to get their first EVC systems on the road. The EVC

37、 system is targeted to operate in temperatures up to 125, while the actuator is targeted to run up to 6000 r/min. Chapter 2 Internal Combustion Engine Automotive engineering English 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. Chapter 2 Inte