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1 Carbon monoxide (CO) also increases the rate at which the photochemical smog is formed by speeding up the conversion of nitric oxide (NO) to nitrogen dioxide.
一氧化碳也增加了光化学烟雾形成的几率。因为一氧化碳促进了一氧化氮向二氧化氮的转变。
2 Oxide of sulfur were initially ignored in the exhaust system, since the sulfur content of gasoline as a fuel is less than 1/10 of 1 percent. Because of this small amount, it was felt that it contributed very little to the overall pollution problem. However, the automobile exhaust system, when equipped with a catalytic converter, changes the sulfur dioxide into sulfur trioxide. When this combines with water vapors, a sulfuric acid mist is formed and is a very difficult pollutant to handle since it is extremely corrosive.
排气系统中的硫氧化合物之前是被忽视的，因为汽油作为燃料，硫的比例小于千分之一。由于这么低的含量，它曾经被认为总污染造成不了多大的影响。但是，装有转换器的排放系统将二氧化硫转换为三氧化硫。当它与水蒸汽混合，就形成了硫酸酸雾。这是非常难于解决的污染物，因为它有强烈的腐蚀性。
3 By visually inspecting the tailpipe emission, a determination can be make as to where an engine to defect may exist. An engine with light gray or blue smoke emitting from the tailpipe normally indicates an increase in the oil consumption through burning due to internal engine wear. Black smoke would indicate a defective fuel delivery system, causing the engine to operate in a rich mode.
通过肉眼观察排气管的排放，可以判断发动机哪里存在问题。发动机排气管排出白色或蓝色烟雾通常表示由于发动机损耗使得耗油量增加。黑色烟雾意味着燃油喷射系统可能存在问题，从而使得发动机运行在浓的工况下。
UNIT 7 THE IGNITION SYSTEM
背景知识：点火系统的基本功用是在发动机各种工况和使用条件下，在气缸内适时、准确、可靠地产生电火花，以点燃可燃混合气，使发动机作功。按其组成和产生高压电方式的不同可分为传统蓄电池点火系统、电子点火系统、微机控制点火系统。? 传统点火系统主要由电源(蓄电池和发电机)、点火开关、点火线圈、电容器、断电器、配电器、火花塞、阻尼电阻和高压导线等组成。
分电器 由断电器、配电器、电容器和点火提前调节装置等组成。它用来在发动机工作时接通与切断点火系统的初级电路，使点火线圈的次级绕组中产生高压电，并按发动机要求的点火时刻与点火顺序，将点火线圈产生的高压电分配到相应气缸的火花塞。
配电器 由分电器盖和分火头组成。用来将点火线圈产生的高压电分配到各缸的火花塞。分电器盖上有一个中心电极和若干个旁电极，旁电极的数目与发动机的气缸数相等。分火头安装在分电器的凸轮轴上，与分电器轴一起旋转。发动机工作时，点火线圈次级绕组中产生的高压电，经分电器盖上的中心电极、分火头、旁电极、高压导线分送到各缸火花塞。 电容器安装在分电器壳上，与断电器触点并联，用来减小断电器触点断开瞬间，在触点处所产生的电火花，以免触点烧蚀，可延长触点的使用寿命。?
There are many different types of ignition systems. Most of these systems can be placed into one of three distinct groups: the conventional breaker point type ignition systems (in use since the early 1,900s); the electronic ignition systems (popular since the mid 70s); and the distributorless ignition system (introduced in the mid 80s).
点火系统有多种不同类型的。其中大部分系统属于（可划分为）以下三种：传统触点型点火
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系统（19世纪早期使用），电子点火系统（从70年代中期开始流行），无分电器点火系统（80年代中期引入）。
The automotive ignition system has two basic functions: it must control the spark and timing of the spark plug firing to match varying engine requirements, and it must increase battery voltage to a point where it will overcome the resistance offered by the spark plug gap and fire the plug. 汽车点火系统有两个基本功能：一是控制火花塞的电点火（能量）以及点火时刻，使其与发动机工作需求相匹配。二是将蓄电池电压升至能够击穿火花塞间隙并产生电火花（点火）的高压。
7.1 Point-Type Ignition System
An automotive ignition system is divided into two electrical circuits - the primary and secondary circuits (Figure 7-1). The primary circuit carries low voltage. This circuit operates only on battery current and is controlled by the breaker points and the ignition switch. The secondary circuit consists of the secondary windings in the coil, the high-tension lead between the distributor and the coil (commonly called the coil wire), the distributor cap, the distributor rotor, the spark plug leads and the spark plugs.
汽车点火系统可分成两个电路，初级电路和次级电路。初级电路提供低压，它只在蓄电池电流下起作用，由断电器和点火开关控制。次级电路包括点火线圈的次级绕组，分电器和点火线圈之间的高压导线，分电器盖，分电器转子（分火头），火花塞引线和火花塞。 distributor rotor分火头 lead 引线，导线
The distributor is the controlling element of the system. It switches the primary current on and off and distributes the current to the proper spark plug each time a spark is needed. The distributor is a stationary housing surrounding a rotating shaft. The shaft is driven at one-half engine speed by the engine’s camshaft through the distributor drive gears. A cam near the top of the distributor shaft has one lobe for each cylinder of the engine. The cam operates the contact points, which are mounted on a plate within the distributor housing.
分电器是系统的控制元件。它控制着初级电流的通断，并把每次点火后所产生的（高压）电流分配至合适的火花塞。配电器是围绕（分电器）转轴的固定壳体。分电器轴由发动机凸轮轴通过分电器传动齿轮驱动，其转速是发动机转速的一半。分电器轴顶端的凸轮凸角数与发动机气缸数相对应。凸轮控制着断电器触点的打开和闭合，断电器触点安装在分电器壳体内的一个金属板上。
Stationary静止的，固定的 1/8页
A rotor is attached to the top of the distributor shaft. When the distributor cap is in place, a spring-loaded piece of metal in the center of the cap makes contact with a metal strip on top of the rotor. The outer end of the rotor passes very close to the contacts connected to the spark plug leads around the outside of the distributor cap. 分火头连接在分电器轴的顶端。当分电器盖在原位不动时，分电器盖中心的弹簧金属片与分电器轴顶端的金属条相接触。分火头外端与分布在分电器盖外围的触点非常接近，触点与火花塞引线相连。
The coil (Figure 7-2) is the heart of the ignition system. Essentially, it is nothing more than a transformer which takes the relatively low voltage (12 volts) available from the battery and increases it to a point where it will fire the spark plug as much as 40,000 volts. The term \perhaps a misnomer since there are actually two coils of wire wound about an iron core. These coils are insulated from each other and the whole assembly is enclosed in an oil-filled case. The
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primary coil, which consists of relatively few turns of heavy wire, is connected to the two primary terminals located on top of the coil. The secondary coil consists of many turns of fine wire. It is connected to the high-tension connection on top of the coil (the tower into which the coil wire from the distributor is plugged).
点火线圈是点火系统的核心（关键）。实质上，它只是一个变压器，将从蓄电池得到的低压升至40000伏的火花塞点火电压。术语线圈可能是误称，因为实际上是两个线圈缠绕着一个铁芯。这些线圈之间彼此绝缘，整个装配浸在油箱中。相对而言，初级绕组匝数很少，导线粗，该绕组两端分别连接到点火线圈上部的两个初级绕组接线柱上。次级绕组匝数较多，它连接在点火线圈上部的高压接头上。 coils of wire线圈，线匝
Under normal operating conditions, power from the battery is fed through a resistor or resistance wire to the primary circuit of the coil and is then grounded through the ignition points in the distributor (the points are closed) . Energizing the coil primary circuit with battery voltage produces current flow through the primary windings, which induces a very large, intense magnetic field. This magnetic field remains as long as current flows and the points remain closed. 在正常工作条件下，蓄电池通过一个电阻器向点火线圈的初级绕组供电，然后，从初级绕组流出的电流又通过断电器触点（位于分电器内部）搭铁（触点闭合时）。接有蓄电池电压的线圈初级电路通电，电流通过初级绕组，会产生一个强磁场。只要有电流且触点闭合，磁场就不会消失（会一直保持）。
As the distributor cam rotates, the points are pushed apart, breaking the primary circuit and stopping the flow of current. Interrupting the flow of primary current causes the magnetic field to collapse. Just as current flowing through a wire produces a magnetic field, moving a magnetic field across a wire will produce a current. As the magnetic field collapses, its lines of force cross the secondary windings, inducing a current in them. Since there are many more turns of wire in the secondary windings, the voltage from the primary windings is magnified considerably up to 40,000 volts.
当（断电器）触点被旋转的分电器凸轮顶开时，初级电路被切断，电流流动停止（消失）。初级电流中断会使（感应）磁场消失。正如电流流过线圈时会产生磁场，磁场穿过线圈也会产生电流。当磁场消失时，磁力线穿过次级绕组，会在次级绕组中产生感应电流。因为次级绕组中有多匝线圈，初级绕组电压会被放大至40000伏。Just as正如
The voltage from the coil secondary windings flows through the coil high-tension lead to the center of the distributor cap, where it is distributed by the rotor to one of the outer terminals in the cap. From there, it flows through the spark plug lead to the spark plug. This process occurs in a split second and is repeated every time the points open and close, which is up to 1,500 times a minute in a 4-cylinder engine at idle.
线圈次级绕组电压通过线圈高压导线引至分电器盖中心（电极），然后由分火头分配至分电器盖内的旁电极，最后通过火花塞线流到火花塞。这个过程是瞬间发生的，在每次断电器触点打开和闭合时重复，对于4缸发动机怠速（运行），每分钟可达到1500次。 split second 瞬间，极短的时间 2/8页
7.2 Electronic Ignition Systems
The need for higher mileage, reduced emissions and greater reliability has led to the development of the electronic ignition systems. These systems generate a much stronger spark, which is needed to ignite leaner fuel mixtures. Breaker point systems needed a resistor to reduce
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the operating voltage of the primary circuit in order to prolong the life of the points. The primary circuit of the electronic ignition systems operates on full battery voltage, which helps to develop a stronger spark. Spark plug gaps have widened due to the ability of the increased voltage to jump the larger gap. Cleaner combustion and less deposit have led to longer spark plug life. 高行驶里程要求，低排放和高可靠性导致电子点火系统的发展。这些系统产生非常强的电火花，用来点燃稀混合气。为了延长触点的使用寿命，触点系统需要一个电阻器来降低初级电路的工作电压。电子点火系统初级电路的工作电压为蓄电池的满电压，它有助于产生强火花。火花塞间隙被加大，因为电压增加，能够击穿更大的间隙。清洁燃烧和低沉淀也会延长火花塞寿命。
On some systems, the ignition coil has been moved inside the distributor cap. This system is said to have an internal coil as opposed to the conventional external one.
在一些系统中，点火线圈被移到分电器盖内。这种系统与传统外部线圈相反，它有一个内部线圈。 as opposed to 与…相反，与…相对比 电子点火系统并不像它们初次出现时那样复杂。事实上，它们只与传统触点式点火系统有稍许不同。与传统点火系统相似，电子系统有两个电路：初级电路和次级电路。整个次级电路与传统点火系统相同。此外，蓄电池和线圈接线柱之间的初级电路也与传统点火系统相同。 Electronic ignition systems differ from conventional ignition systems in the distributor component area. Instead of a distributor cam, breaker plate, points, and condenser, an electronic ignition system has an armature (called by various names such as a trigger wheel, reluctor, etc.), a pickup coil (stator, sensor, etc.), and an electronic control module.
电子点火系统与传统点火系统不同的地方在于分电器区域。电子点火系统使用电枢，传感线圈（定子，传感器等）以及电子控制模块来代替分电器凸轮，断电器金属板，断电器触点和电容器。电枢有各种各样的名字，比如触发轮，磁组分配头等等。
Armature电枢reluctor磁组分配头pickup coil传感线圈，拾波线圈，感应线圈 7.3 Distributorless Ignition Systems (DIS)
The third type of ignition system is the distributorless ignition. The spark plugs are fired directly from the coils. The spark timing is controlled by an Ignition Control Unit (ICU) and the Engine Control Unit (ECU). The distributorless ignition system may have one coil per cylinder, or one coil for each pair of cylinders.
第三种点火系统是无分电器点火系统。火花塞由点火线圈直接点燃。点火正时由点火控制单元和发动机控制单元控制。无分电器点火系统每气缸或每对气缸有一个点火线圈。
Some popular systems use one ignition coil per two cylinders. This type of system is often known as the waste spark distribution method. In this system, each cylinder is paired with the cylinder opposite it in the firing order (usually 1-4, 2-3 on 4-cylinder engines or 1-4, 2-5, 3-6 on V6 engines, Figure 7-4). The ends of each coil secondary leads are attached to spark plugs for the paired opposites. These two plugs are on companion cylinders, cylinders that are at Top Dead Center (TDC) at the same time. But, they are paired opposites, because they are always at opposing ends of the 4-stroke engine cycle. When one is at TDC of the compression stroke, the other is at TDC of the exhaust stroke. The one that is on compression is said to be the event cylinder and one on the 3/8页
exhaust stroke, the waste cylinder. When the coil discharges, both plugs fire at the same time to complete the series circuit.
一些通用系统每两个气缸有一个点火线圈。这种系统常被称为废火（同时点火）分配方式。
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这个系统中，点火时序相反的两个气缸配成一对（分为一组），对于4气缸发动机，通常为1-4, 2-3，或6气缸发动机的1-4, 2-5, 3-6。每个线圈次级（绕组）导线一端（同时）连接到这对气缸的火花塞上，一对气缸上有两个火花塞，两个气缸同时达到上止点。但是其配对相反，因为它们总是位于4冲程发动机循环周期相反的一端。当其中一个处于压缩冲程的上止点，另一个则处于排气冲程的上止点。处于压缩冲程的气缸据说是做功（有效）气缸，而位于排气冲程的气缸是废缸。当点火线圈放电时，串联在一起的两个火花塞在同一时间完成点火。
Be known as 被称为event事件，过程，冲程
Since the polarity of the primary and the secondary windings are fixed, one plug always fires in a forward direction and the other in reverse. This is different than a conventional system firing all plugs the same direction each time. Because of the demand for additional energy; the coil design, saturation time and primary current flow are also different. This redesign of the system allows higher energy to be available from the distributorless coils, greater than 40 kilovolts at all rpm ranges.
因为初级绕组和次级绕组的极性是固定的，所以一个火花塞总是正向发火，而另一个总是反向发火。（指电流流动方向）这与传统系统每次对所有火花塞按同一方向点火不同。因为它需要附加（点火）能量，所以线圈设计，磁饱和时间和初级电流流动也不同。系统重新设计可从无分电器点火线圈获得更高的点火能量，在全部转速范围内，可超过40千伏。 Be different than 不同于
The distributorless ignition system uses either a magnetic crankshaft sensor, camshaft position sensor, or both, to determine crankshaft position and engine speed. This signal is sent to the ignition control module or engine control module, which then energizes the appropriate coil. 无分电器点火系统可采用磁性曲轴传感器，凸轮轴位置传感器，或两者相结合来测定曲轴位置和发动机转速。（测量）信号被发送至点火控制模块或发动机控制模块，然后由它对相应点火线圈通电。
The advantages of no distributor, in theory, are: 1. No timing adjustments.
2. No distributor cap and rotor. 3. No moving parts to wear out.
4. No distributor to accumulate moisture and cause starting problems. 5. No distributor to drive thus providing less engine drag. 无分电器（点火系统），理论上的优点在于：不需要调整点火时间，没有分电器盖和分火头，没有运动部件磨损，不会发生分电器受潮所引起的起动问题，不需要驱动分电器，因此可减小发动机（转动）阻力。
The major components of a distributorless ignition are: 1. ECU or Engine Control Unit. 2. ICU or Ignition Control Unit.
3. Magnetic Triggering Device such as the Crankshaft Position Sensor and the Camshaft Position Sensor. 4. Coil Pack.
无分电器点火系统的主要组成有：ECU（即发动机控制单元），ICU（即点火控制单元），磁性触发器设备，比如曲轴位置传感器和凸轮轴位置传感器，线圈组件（Coil Pack）。 4/8页 EXERCISES
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