排气控制系统课程毕业设计外文文献翻译、中英文翻译、外文翻译

1 英文资料翻译  Emission Control Systems The purpose of the emission system is just that it controls the emission and exhaust from a vehicle. The idea is to turn the harmful gases a car manufactures into harmless ones that don't ruin the environment, or persons. Some of problem gases are: 1. hydrocarbons（ unburned） . 2. Carbon monoxide. 3. Carbon dioxide 4. Nitrogen oxide. 5. Sulfur dioxide. 6. Phosphorus. 7. Lead and other metal. There are five popular systems used to reduce emissions: the crankcase ventilation system, the evaporative emissions control system, the exhaust gas recirculation system and the catalytic converter system. In additional to these emissions system, some vehicles incorporate an electronically controlled fuel system, which further reduces emissions. Note: Not all vehicles are equipped with these emission systems. Crankcase ventilation system Since the early 1960s, all cars have been equipped with crankcase ventilation system. When the engine is running, a small portion of the gases which are formed in the combustion chamber leak pas the piston rings and enter the crankcase.  Since these gases are under pressure, they tend to escape from the crankcase and enter the atmosphere. if these gases are allowed to remain in the crankcase for any length of time, they contaminate the engine oil and cause sludge to build up in the crankcase. If the gases are allowed to escape to the atmosphere,  they pollute the air with unburned hydrocarbons. The job of the crankcase ventilation  2 system is to recycle thee gases back into the engine combustion chamber where they are re-burned. The crankcase gases are recycled as the engine is running by drawing clean filtered air through the air filter and into the crankcase.  As they are passes through the crankcase, it picks up the combustion gases and carries them out of the crankcase, through the oil separator, through the PCV valve or orifice, and into the induction system. as they enter the intake manifold, they are drawn into the combustion chamber where they are re-burned. The most critical component in the system is the PCV valve that controls the amount of gases that are recycled. At low engine speed increases, the valve opens to admit greater quantities of air to the intake manifold. Some systems do not use a PCV valve. They simply use a restrictor or orifice in the ventilation hose to meter the crankcase gases. If the PCV valve becomes blocked or plugged, the gases can not be vented from the crankcase. Since they are under pressure, they ill find their own way out of the crankcase. This alternate route is usually a weak oil seal or gasket in the engine. As the gas escapes by the gasket, it usually creates an oil leak. Besides causing oil leaks, a clogged PCV valve also allows these gases to remain in the crankcase for an extended period, promoting the formation of sludge in the engine. Evaporative emission control system The evaporative emission control system is designed to prevent fuel tank and carburettor bowl vapours from being emitted into the atmosphere.  Fuel vapours are absorbed and stored by a fuel vapour charcoal canister. The canister stores them until certain engine conditions are met and the vapours can be purged and burned by the engine. The charcoal canister purge cycle is controlled different ways: either by a thermostatic vacuum switch, a solenoid or by a timed vacuum source. The thermostatic switch is installed in the coolant passage and prevents canister purge when the engine is below a certain temperature. The solenoid is usually controlled by a computer and is used on feedback fuel systems. The computer  3 determines when canister purge is appropriate. Depending on the system, this can be engine operating temperature, engine speed, evaporative system pressure or any combination of these. The timed vacuum source uses a manifold vacuum controlled diaphragm o control canister purge. When the engine is running, full manifold vacuum is applied to the top tube of the purge valve which lifts the valve diaphragm and opens the valve. A vent located in the fuel tank, allows fuel vapours to flow to the charcoal canister. a tank pressure control valve, used on some high altitude applications, prevents canister purge when the engine is not running. The fuel tank cap does not normally vent to the atmosphere, but is designed to provide both vacuum and pressure relief. Air injection system Introducing a controlled amount of air into the exhaust system promotes further oxidation of the gases. This in turn reduces the amount of carbon monoxide and water, the harmless by-products of combustion. Some system use an air pump, while other use negative exhaust pulses to draw air. The air pump, usually driven by a belt, simply pumps air under a pressure of only a few pounds into each exhaust port. Between the nozzles and the pump is a check valve to keep the hot exhaust gases from flowing back into the pump and hoses thereby destroying them. Most pumps also utilize a gulp valve or a diverter valve. Early system used a gulp valve while later systems use diverter valves.  They both operate on the same principle. During deceleration, as the throttle is closed, the explosion in the exhaust system could occur that could blow the muffler apart. During deceleration, the air is either diverted into the atmosphere or into the intake system. On pulse air system, clean air is drawn through a silencer, the check valve and then into the exhaust ports. The negative exhaust pulses opens the reed valve in the check valve assembly, allowing air to flow into the exhaust port. Some feedback-controlled vehicles utilize an oxidizing catalytic converter. Under certain operating conditions, the air is diverted into the catalytic converter to help oxidize the exhaust gases.  4 Exhaust gas re-circulation system The EGR system's purpose is to control oxides of nitrogen which are formed during the combustion process. NOx emissions at low combustion temperatures are not severe, but when the combustion temperatures go over 2,500F, the production of NOx in the combustion chambers shoots way up. The end products of combustion are relatively inert gases derived from the exhaust gases. these are redirected ,(under certain conditions) through the EGR valve and back into the combustion chamber. These inert gases displace a certain amount of oxygen in the chamber. Since not as much chamber. These inert gases displace a certain amount of oxygen in the chamber. Since not as much oxygen is present, the explosion is not as hot. This helps lower peak combustion temperatures. The EGR valve can either be actuated by a vacuum diaphragm,  a solenoid or stepper motor. On feedback controlled vehicles, the EGR system is controlled by the computer. Catalytic converter The catalytic converter is a muffler-like container built into the exhaust system to aid in the reduction of exhaust emissions. The catalyst element is coated with a noble metal such as platinum, palladium, rhodium or a combination of hem, when the exhaust gases come into harmless substances such as water and carbon dioxide, oxidizing catalysts into H2O and CO2. While catalytic converters are built in a variety of shapes and sizes, they all fall into two general types, the pellet, or bead type and the monolithic type. Construction may differ slightly, but the object is the same -to present the largest possible surface area to passing exhaust gases. Older vehicles use bead type converters. The exhaust gas must pass through a bed of these pellets. This type of converter is rather restrictive. The cross-section of a monolithic type converter resembles a honeycomb. The exhaust gases are exposed to a greater amount of surface area in these converters; as a result they are more efficient. They also tend to be less restrictive. Dual exhaust system The advantage of a dual exhaust system is that the engine exhausts more  5 freely, thereby lowering the backpressure, which is inherent in an exhaust .with a dual exhaust system, a sizable increase in engine horsepower can be obtained because the breathing capacity of the engine is improved, leaving less exhaust gases in the engine at the end of each exhaust stroke. This in turn, leaves more room for an extra intake of the air-fuel mixture. Hyperboloid gear On the passenger vehicle main gear box uses the hyperbolic curve gear generally. This is because the hyperbolic curve gear and the spiral bevel gear compare, former revolut ion noise few, work steadier, turns the tooth intensity high, moreover also has the drive gear spool thread to be possible the relative driven gear disalignment characteristic, this point to be extremely important regarding the automobile technical performance, engineer may in not change the engine the position size to be possible to change the driving axle directly the ground clearance, also is changes the entire vehicle the ground clearance. some automobiles main gear box hyperbolic curve gear off-sets amounts to more than 30 millimeters, in the maintenance certain ground clearance situation, may reduce the drive gear and the drive shaft position, causes the automobile body center of gravity to reduce, is advantageous in enhances the automobile high speed travel the stability. Two gears spool threads intersection driving pulley displaces to under   Some automobiles produce the passenger vehicle and movement on the identical frame, its chassis parameter transformation also has used hyperbolic curve gear this characteristic. Because has these merits, at present the automobile driving axle already tended to uses the hyperbolic curve gear, in fact recent years imported the automobile basically was uses the hyperbolic curve gear, the domestically produced automob ile also has many vehicle types to use the hyperbolic curve gear, and already more and more were many in center, on the heavy freight vehicle obtains the use.  When the hyperbolic curve gear works, between the tooth face can have in a big way skids relatively, also the tooth face pressure is very big, the tooth face lubricant film is easily destroyed. In order to reduce the friction, enhances the  6 efficiency, must have to use includes guards against the abrasion chemical additive the special-purpose hyperbolic curve gear oil, cannot use other gear oil to replace, otherwise will cause the tooth face rapid attrition and the abrasion, seriously will affect the automobile the running status. Further development Manufacturers around the world are seeking significant improvements in conventional automotive technologies, and Chinese manufacturers risk falling behind if they fail to sustain comparable research efforts on conventional power train systems. The Chinese automotive industry also should strengthen its effor ts to develop improved diesel and spark ignition technology in cooperation with its joint venture partners. Researchers should focus on .among other things, advanced gasoline and diesel engine technologies, an ultra-low-emission gasoline engine system, diesel particulate filters, de-NO catalysts, selective catalytic reduction (SCR), and improved in-engine combustion management. Industry must develop the capability to model the vehicle power train system in order to optimize its overall performance, including fuel economy, and vehicle drivability. The automobile's further development will be determined by already existing and steadily increasing requirements, by additional further requirements and by the technical possibilities for meeting these requirements. The following focal point for development and research efforts can be discerned. Further improvement of the automobile through product innovation is in all classic functions, performance, fuel economy, environmental impact, safety, comfort, and reliability.   7 中  文  翻  译  排气控制系统  排放 控制 系统的目的 只 是 为了 控制车辆废气的排放。这个想法是把有汽车 排放的有 害气体 变 为无害， 从而 不破坏环境，或 影响人们的健康 。 这些有害 气体是：  1.未完全燃烧的 碳氢化合物 ；  2. 一氧化碳 ；  3. 二氧化碳 ；  4. 氮氧化物 ；  5.二氧化硫；  6.磷；  7. 铅和其他金属 。  通常 有 5 类 系统 用 来减少排放量：曲轴箱通风系统， 燃油 蒸发排放控制系统，废气再循环系统和催化转换器系统。除了这些排放系统，将一些车辆的电子控制燃油系统，从而进一步降低排放量。  注意：并非 所有的车辆都配备了这些排放系统 。  曲轴箱通风系统  自 1960 年代初以来，所有车辆都配备了曲轴箱通风系统。  当发动机运行时，一小部分 在 燃烧室形成 的 气体 从 活塞环泄漏 从而 进入曲轴箱。由于这些气体的 处高 压力下，他们往往摆脱曲轴箱，进入大气层。如果这些气体被允许留在曲轴箱 一段 时间，它们 将 污染机油，造成污泥， 集聚在 曲轴箱。如果气体逃脱到大气中，他们 中 的未燃尽碳氢化合物 将 污染空气。曲轴箱通风系统 的作用是 回收 气体 进入发动机燃烧室， 使其 重新 燃 烧。  曲轴箱 泄露的 气体 被 回收利用 ，当 发动机 运行时采用 用清洁过滤 使 空气通过空气 过滤器进入曲轴箱。 当 它们通过曲轴箱 时 ，它通过 分油器 ，通过 强 8 制式通风 阀或孔， 将 燃烧气体 带离 曲轴箱， 进入循环系统 。他们 由 进气歧管卷入燃烧室， 在那 重新被 燃烧 。  该循环系统 最重要的组成部分是 强制式通风 阀 ，它用来 控制 废气的 循环利用 量 。在低 时随着 转速的增加，阀打开接纳更多的空气的进 入进 气歧管。有些 循环系统 不使用 强制式通风 阀。他们只是使用或孔板节流的通风管，以控制 曲轴箱气体。  如果 强制式通风 阀 被 拦截或堵塞，气体无法从曲轴箱通风。 从而导致 他们 在高 压下， 通过密封间隙逃离 曲轴箱。这种 气体的泄露 通常是 由于 引擎 内一个薄弱油封或垫圈 。随着气体 通过 垫圈逸出，它通常 伴随着 油 的 泄漏。除了造成油泄漏 污染 ，阻塞 强制式通风 阀 也将导致 这些气体留在曲轴箱的 时间延长， 从而导致形成发动机油泥污染 。  燃油 蒸发排放控制系统  燃油 蒸发排放控制系统的设计， 是为 防止油箱和化油器 的 气体被排放到大气中。燃油蒸汽吸收 并 储存 在活性 炭罐 中 。 当 某些发动机条件得到满足 时油气混合 蒸汽 将被净化并通过发动机燃烧 。  活性 炭罐 净化系统以几种 不同的方式控制：要么由一个恒温真空开关，电磁或定时真空源 控制 。恒温开关安装在冷却通道，防止罐清洗发动机时低于某一温度。电磁通常是由计算机控制的 ，用于燃油系统的反馈。计算机决定何时罐清洗是适当的。 通过这些 系统 反馈 ，这可能是发动机的工作温度，发动机转速，蒸发系统压力或任何这些 条件 的组合。定时真空源使用多种真空控制隔膜控制 活性罐 。当发动机运行时， 只够的企管真空压力作用于进气阀门顶端 ， 并使 阀门膜片升 起从而 打开阀门。  一个位于油箱 的 通风口，使燃油蒸汽流向 活性 炭罐。 油箱压力 控制阀，用于在一些高海拔地区的应用，防止发动机未运行 时活性碳罐工作 。油箱盖通常不会 朝大气开合 ，但 能提供真空和可靠的压力条件 。   空气喷射系统   9 将一定 控制量的空气 导 入排气系统促进气体 的 进一步 氧化。这反过来又减少了一氧化碳和 碳氢化合物 ，无害的燃烧副产品。有些系统使用的空气泵，而其他使用排气脉冲提 来吸取 空气。   空气泵，通常 由皮 带带动，只要 在 只有少数磅 的空气压力下就能传送空气 到每个排气口。 位于 喷嘴和泵之间的是一个止回阀保持热废气流回到泵和软管从而破坏它们。大多数泵还利用 补气阀 或 横向 阀。早期的系统使用了 补气阀 而后来系统使用 横向 阀。他们都 基于 同样的原 理 。在减速 时 ，因为油门是封闭的， 燃油混合气变得越来越多。如果混合气继续增多， 爆在排气系统中 就 可能发生 爆炸 ，可能 使 消声器分 离 。在减速 期间 ，空气要么改 行到大气中或到进气系统。   在 脉冲空气系统 中 ， 来自空气滤清器的清洁空气经过消声器 ，止回阀，然后到排气口。排气 负 脉冲打开止回阀 的 簧片阀，使空气流入排气口。   一些反馈控制的车辆利用氧化催化转化器。在某些工作条件下，空气转入催化转换器，以帮助氧化废气 。  废气再循环系统  废气再循环 系统的目的是控制燃烧过程中形成的氮氧化物。  NOx 在 燃烧温度低 时 排放并不 多 ，但是，当