货车驱动桥设计英文资料翻译
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:
- hydrocarbons（unburned）.
- Carbon monoxide.
- Carbon dioxide
- Nitrogen oxide.
- Sulfur dioxide.
- Phosphorus.
- 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 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 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.
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 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 revolution 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 automobile 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 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 efforts 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.
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
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，当燃烧温度超过2500，燃烧室生产的NOx急剧增加。来源于废气的燃烧最终产品是相对惰性的气体。它们改变向， （在某些情况下）通过废气再循环阀流回到燃烧室。这些惰性气体取代一定量的燃烧室内的氧气。由于没有了充足的氧气，燃烧将不充分。这有助于降低最高燃烧温度。
废气再循环阀可以是由真空膜片，电磁或步进电机驱动。反馈控制的车辆， EGR系统由计算机控。
催化转化器
催化转换器是在排气系统中建立的一个消声器类装置，用来减少废气排放。该催化剂单元 是涂有贵金属，如铂，钯，铑或它们的任意组合，如果废弃与催化剂接触，化学反应就会发生，从而就可以将污染物转换为水和CO2的无害物质。
尽管催化转化器的形状和大小各种各样，但都可以归结为两种基本类型：颗粒型和整体型。工作方式可能略有不同，但目标是相同的，即提供最大的可能表面积来输送废气。旧车辆使用颗粒型转换器。废气必须通过一层颗粒。这种类型的转换是相当局限的。整体型转换器的主要组成是一类似于蜂窝物体。在这些转换器废气接触到更大量的表面积，由于他们更有效率。他们也往往是局限性较少。
双排气系统
双排气系统的的优点是，发动机排出废气更自由，从而降低了背压，这是一种固有的排气。由于有双排气系统，引擎马力可以大大增加因为引擎呼吸能力的改善，使发动机在每一排气冲程中排放废气量少。这反过来又导致有更多的空间来吸收更多的空气燃料的混合物。
双曲面齿轮
轿车上的主减速器一般采用双曲线齿轮。这是因为双曲线齿轮与螺旋锥齿轮比较，前者运转噪音少，工作更平稳，轮齿强度较高，而且还具有主动齿轮轴线可以相对从动齿轮轴线偏移的特点，这一点对于汽车的技术性能非常重要，工程师可以在不改变发动机的位置尺寸就可以直接改变驱动桥的离地间隙，也就是改变整部车的离地间隙。
有些汽车在同一车架上生产轿车和运动休闲车，其底盘的参数变换也是利用了双曲线齿轮这一特性。由于有这些优点，目前汽车的驱动桥已经趋向于用双曲线齿轮，实际上近年进口汽车基本上是采用双曲线齿轮，国产汽车也有许多车型采用双曲线齿轮，并已经越来越多地在中、重型货车上得到采用。
但双曲线齿轮工作时，齿面间会有较大的相对滑动，且齿面压力很大，齿面油膜容易被破坏。为减少摩擦，提高效率，必须要采用含有防刮伤添加剂的专用双曲线齿轮油，绝不能用其它的齿轮油代替，否则将使齿面迅速磨损和擦伤，严重影响汽车的运行状态。
未来发展
世界各汽车制造商都在对传统汽车技术进行重大改进。如果中国的汽车企业不在汽车传统传动系统研究上付出相应的努力，将有落后于世界其他汽车企业的危险。中国的汽车工业应与其合资伙伴进行或做，加强发展改良的柴油发动机和火花点火技术。研究人员也应把重点放在先进的汽油和柴油发动机技术、超低排放汽油发动机系统、柴油机微粒过滤器、去氮氧化物催化剂、选择催化还原（SCR），以及改进的机内燃烧控制系统上。汽车工业必须设法模拟汽车传动系统的能力，以便优化整体性能，包括燃料经济性、排放及车辆的驾驶性能。未来汽车的深层次发展将由已经存在和正在缓慢提高的需求和额外的附加要求以及为满足这些要求所需技术方面的可能性来决定。接下来关于发展和研究成果方面将成为人们的焦点。汽车业通过在各项传统功能如：性能，燃油经济性，环境影响，安全，舒适，可靠性方面对产品改进而得到进一步发展。