外文翻译--燃油喷射系统

附 录 附录 A 英文文献与中文参考译文 A1Fuel injection systems A1.1 General information Fuel injection systems have been used on vehicles for many years. The earliest ones were purely mechanical. As technology advanced, electronic fuel injection systems became more popular. Early mechanical and electronic fuel injection systems did not use feedback controls. As emissions became more of a concern, feedback controls were adapted to both types of fuel injection systems. Both mechanical and electronic fuel injection systems can be found on gasoline engines. A1.2 Multi-port fuel injections This is the most common type of fuel injection system found today. Regardless of the manufacturer, they all function in the same basic way. On these systems an equal amount of fuel is delivered to each cylinder. These systems all use sensors which transmit operating conditions to the computer. Information from these sensors is processed by the computer which then determines the proper air/fuel mixture. This signal is sent to the fuel injectors which open and inject fuel into their ports. The longer the injector is held open, the richer the fuel mixture will be. Most fuel injection systems need the following information to operate properly. Temperature sensors-this includes both air and coolant temperature. The computer determine how rich or lean the mixture should be. The colder the temperature, the richer the mixture. Throttle position sensors or switches-the computer uses this information to determine the position of the throttle valve(s). Some vehicles use sensors which relay the exact position of the throttle valve(s) at all times. Others use switches which only relay closed and wide-open throttle positions (some may also use a mid-throttle switch). These switches and sensors help determine engine load. Airflow sensors-these sensors also help the computer determine engine load by indicating the amount of air entering the engine. There are several different types of airflow sensors, but in the end, they all do the same job. Manifold pressure sensors-if a vehicle is not equipped with an airflow sensor, it uses a manifold pressure sensor to determine engine load (Note that some vehicles with an airflow sensor may also have a manifold pressure sensor. This is used as a fail-safe if the airflow sensor fails). As engine load increases, so does intake manifold air pressure. Engine speed and position sensors-engine speed/position sensors can be referenced form the crankshaft, camshaft or both. In addition to helping determine engine load, these sensors also tell the computer when the injectors should be fired. These systems operate at a relatively high pressure(usually at least 30 psi). To control the fuel pressure, a fuel pressure regulator is used. As engine load increases, more fuel pressure is needed. This is due to the richer mixture (more fuel needed) and to overcome the increased air pressure in the ports. Any unused fuel is diverted back to the fuel tank using a return line. A2. Ignition system 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 1900s)； the electronic ignition systems (popular since the mid 70s)； and the distributorless ignition system (introduced in the mid 80s). 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. A2.1How does the ignition system work An automotive ignition system is divided into two electrical circuitsthe primary and secondary circuits. 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) on external coil distributors, the distributor cap, the distributor rotor ,the spark plug leads and the spark plugs. 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 engines 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. 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. The coil 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 40000 volts. The term “coil” is 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 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). 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 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. 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 40000 volts18,19. 参考译文： A1.燃油喷射系统 A1.1 燃油喷射系统概述 燃料喷射系统已经在汽上车使用了许多年。最早的部分是纯粹机械的。对于先进的技术，电子燃料喷射系统变得更加普遍。早期的机械式和电子式燃料喷射系统没有使用反馈控制。当今与排放越来越相关，两种燃油喷射系统反馈控制都适应。机械和电子式燃料喷射系统在汽油发动机上比较长见。 A1.2多点燃油喷射 系统 这是今天被使用的燃料喷射系统中最普通的类型。所有的制造商，他们都使用同一个基本的方式。它是将等量的混合气分配到各个气缸中。 燃油系统都是通过传感器输送的信号给计算机控制。通过计算机处理传感器的信号，然后确定适当的空燃比。然后将喷油信号送给喷油器，控制喷油器的开启和关闭。喷油器打开的时间越长，进入气缸的混合气越多。大部分燃油喷射系统需要以下传感器信号正常运作。 温度传感器，这里面包括空气和冷却液的温度。计算机通过温度传感器来确定混合气的浓度。低温时，使混合气变浓。 节气门位置传感器，电脑根据此信号来确定 节气门的开闭。一些车辆在任何时候都使用节气门位置传感器，从而确定节气门的具体位置。其他车辆使用传感器确定节气门关闭和节气门打开位置（有些还可以使用怠速开关）。这些开关和传感器，帮助确定发动机负荷。 空气流量传感器，该传感器还有助于计算机确定发动机的进气量，用于表示发动机负荷。有几种不同类型的空气流量计，不过，他们的作用是相同的。 进气压力传感器，如果车辆没有配备空气流量传感器，则它采用了进气压力传感器，以确定发动机负荷（请注意，一些车辆的空气流量传感器也可能有进气压力传感器。这是作为一个空气流量传感器故障的 后备安全故障）。进气歧管空气压力增大则表示发动机负荷增大。 发动机的 转速 和位置传感器，发动机转速 和 位置传感器可 从 曲轴 、 凸轮轴 得到信号 。除了 可以 确定发动机负荷， 还可以通过传感器确定进气量 。 燃油喷射 系统 工作 在一个相对较高的压力（通常至少 30 磅） 环境下 。燃油压力调节器 用来 控制燃油压力 ，使燃油压力保持恒定 。 如果 发动机负荷增加，更省油的压力是必要的。 这是由于混合气变浓 （需要更多的燃料），并克服空气压力。任何未使用的燃料 都通过回油管 回到油箱。 A2点火系统 点火系统有许多不同类型。大多数点火系统可分为三种：传统的断路 器点火系统（自 20 世纪初期以来使用）；电子点火系统（流行于 70 年代中期）和微机控制点火系统（发展于 80年代中期）。 汽车点火系统有两个基本功能，首先它必须能够控制火花的大小和点火时刻，以配合不同发动机的要求；其次它必须能够增加电池电压以克服火花塞两极间的电阻来产生火花。 A2.1点火系统如何工作 点火系统电路由两部分组成 初级电路和次级电路。次级电路承载着较低的电压。电池电流从该电路流过，并由断电器和点火开关控制通断。次级电路由火花塞、高压线、分电器分火头、次级点火线圈组成。 分电器是点火系统的控制部分。它 将初级电流接通或断开，并将电流送到相应的火花塞上。分电器轴以低于曲轴一半的转速旋转。分电器轴附近的凸轮轴有一个凸起对应着相应的汽缸。 转子连接在分电器轴的顶部。当分火头置位时，一个弹簧挤压着金属块使之与转子上的金属带连接。转子的尾端与火花塞末端紧密连接使之发火。 点火线圈是点火系统的核心。从本质上讲，它只不过是一个变压器，将电池的低电压