KD1060型貨車驅動橋設計
KD1060型貨車驅動橋設計,kd1060,貨車,驅動,設計
英文資料翻譯
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 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 譯
排氣控制系統(tǒng)
排放控制系統(tǒng)的目的只是為了控制車輛廢氣的排放。這個想法是把有汽車排放的有害氣體變?yōu)闊o害，從而不破壞環(huán)境，或影響人們的健康。這些有害氣體是：
1.未完全燃燒的碳氫化合物；
2. 一氧化碳；
3. 二氧化碳；
4. 氮氧化物；
5.二氧化硫；
6.磷；
7. 鉛和其他金屬。
通常有5類系統(tǒng)用來減少排放量：曲軸箱通風系統(tǒng)，燃油蒸發(fā)排放控制系統(tǒng)，廢氣再循環(huán)系統(tǒng)和催化轉換器系統(tǒng)。除了這些排放系統(tǒng)，將一些車輛的電子控制燃油系統(tǒng)，從而進一步降低排放量。
注意：并非所有的車輛都配備了這些排放系統(tǒng)。
曲軸箱通風系統(tǒng)
自1960年代初以來，所有車輛都配備了曲軸箱通風系統(tǒng)。
當發(fā)動機運行時，一小部分在燃燒室形成的氣體從活塞環(huán)泄漏從而進入曲軸箱。由于這些氣體的處高壓力下，他們往往擺脫曲軸箱，進入大氣層。如果這些氣體被允許留在曲軸箱一段時間，它們將污染機油，造成污泥，集聚在曲軸箱。如果氣體逃脫到大氣中，他們中的未燃盡碳氫化合物將污染空氣。曲軸箱通風系統(tǒng)的作用是回收氣體進入發(fā)動機燃燒室，使其重新燃燒。
曲軸箱泄露的氣體被回收利用，當發(fā)動機運行時采用用清潔過濾使空氣通過空氣過濾器進入曲軸箱。當它們通過曲軸箱時，它通過分油器，通過強制式通風閥或孔，將燃燒氣體帶離曲軸箱，進入循環(huán)系統(tǒng)。他們由進氣歧管卷入燃燒室，在那重新被燃燒。
該循環(huán)系統(tǒng)最重要的組成部分是強制式通風閥，它用來控制廢氣的循環(huán)利用量。在低時隨著轉速的增加，閥打開接納更多的空氣的進入進氣歧管。有些循環(huán)系統(tǒng)不使用強制式通風閥。他們只是使用或孔板節(jié)流的通風管，以控制曲軸箱氣體。
如果強制式通風閥被攔截或堵塞，氣體無法從曲軸箱通風。從而導致他們在高壓下，通過密封間隙逃離曲軸箱。這種氣體的泄露通常是由于引擎內一個薄弱油封或墊圈。隨著氣體通過墊圈逸出，它通常伴隨著油的泄漏。除了造成油泄漏污染，阻塞強制式通風閥也將導致這些氣體留在曲軸箱的時間延長，從而導致形成發(fā)動機油泥污染。
燃油蒸發(fā)排放控制系統(tǒng)
燃油蒸發(fā)排放控制系統(tǒng)的設計，是為防止油箱和化油器的氣體被排放到大氣中。燃油蒸汽吸收并儲存在活性炭罐中。當某些發(fā)動機條件得到滿足時油氣混合蒸汽將被凈化并通過發(fā)動機燃燒。
活性炭罐凈化系統(tǒng)以幾種不同的方式控制：要么由一個恒溫真空開關，電磁或定時真空源控制。恒溫開關安裝在冷卻通道，防止罐清洗發(fā)動機時低于某一溫度。電磁通常是由計算機控制的，用于燃油系統(tǒng)的反饋。計算機決定何時罐清洗是適當?shù)?。通過這些系統(tǒng)反饋，這可能是發(fā)動機的工作溫度，發(fā)動機轉速，蒸發(fā)系統(tǒng)壓力或任何這些條件的組合。定時真空源使用多種真空控制隔膜控制活性罐。當發(fā)動機運行時，只夠的企管真空壓力作用于進氣閥門頂端，并使閥門膜片升起從而打開閥門。
一個位于油箱的通風口，使燃油蒸汽流向活性炭罐。油箱壓力控制閥，用于在一些高海拔地區(qū)的應用，防止發(fā)動機未運行時活性碳罐工作。油箱蓋通常不會朝大氣開合，但能提供真空和可靠的壓力條件。
空氣噴射系統(tǒng)
將一定控制量的空氣導入排氣系統(tǒng)促進氣體的進一步氧化。這反過來又減少了一氧化碳和碳氫化合物，無害的燃燒副產品。有些系統(tǒng)使用的空氣泵，而其他使用排氣脈沖提來吸取空氣。
空氣泵，通常由皮帶帶動，只要在只有少數(shù)磅的空氣壓力下就能傳送空氣到每個排氣口。位于噴嘴和泵之間的是一個止回閥保持熱廢氣流回到泵和軟管從而破壞它們。大多數(shù)泵還利用補氣閥或橫向閥。早期的系統(tǒng)使用了補氣閥而后來系統(tǒng)使用橫向閥。他們都基于同樣的原理。在減速時，因為油門是封閉的，燃油混合氣變得越來越多。如果混合氣繼續(xù)增多，爆在排氣系統(tǒng)中就可能發(fā)生爆炸，可能使消聲器分離。在減速期間，空氣要么改行到大氣中或到進氣系統(tǒng)。
在脈沖空氣系統(tǒng)中，來自空氣濾清器的清潔空氣經過消聲器，止回閥，然后到排氣口。排氣負脈沖打開止回閥的簧片閥，使空氣流入排氣口。
一些反饋控制的車輛利用氧化催化轉化器。在某些工作條件下，空氣轉入催化轉換器，以幫助氧化廢氣。
廢氣再循環(huán)系統(tǒng)
廢氣再循環(huán)系統(tǒng)的目的是控制燃燒過程中形成的氮氧化物。 NOx在燃燒溫度低時排放并不多，但是，當燃燒溫度超過2500，燃燒室生產的NOx急劇增加。來源于廢氣的燃燒最終產品是相對惰性的氣體。它們改變向， （在某些情況下）通過廢氣再循環(huán)閥流回到燃燒室。這些惰性氣體取代一定量的燃燒室內的氧氣。由于沒有了充足的氧氣，燃燒將不充分。這有助于降低最高燃燒溫度。
廢氣再循環(huán)閥可以是由真空膜片，電磁或步進電機驅動。反饋控制的車輛， EGR系統(tǒng)由計算機控。
催化轉化器
催化轉換器是在排氣系統(tǒng)中建立的一個消聲器類裝置，用來減少廢氣排放。該催化劑單元 是涂有貴金屬，如鉑，鈀，銠或它們的任意組合，如果廢棄與催化劑接觸，化學反應就會發(fā)生，從而就可以將污染物轉換為水和CO2的無害物質。
盡管催化轉化器的形狀和大小各種各樣，但都可以歸結為兩種基本類型：顆粒型和整體型。工作方式可能略有不同，但目標是相同的，即提供最大的可能表面積來輸送廢氣。舊車輛使用顆粒型轉換器。廢氣必須通過一層顆粒。這種類型的轉換是相當局限的。整體型轉換器的主要組成是一類似于蜂窩物體。在這些轉換器廢氣接觸到更大量的表面積，由于他們更有效率。他們也往往是局限性較少。
雙排氣系統(tǒng)
雙排氣系統(tǒng)的的優(yōu)點是，發(fā)動機排出廢氣更自由，從而降低了背壓，這是一種固有的排氣。由于有雙排氣系統(tǒng)，引擎馬力可以大大增加因為引擎呼吸能力的改善，使發(fā)動機在每一排氣沖程中排放廢氣量少。這反過來又導致有更多的空間來吸收更多的空氣燃料的混合物。
雙曲面齒輪
轎車上的主減速器一般采用雙曲線齒輪。這是因為雙曲線齒輪與螺旋錐齒輪比較，前者運轉噪音少，工作更平穩(wěn)，輪齒強度較高，而且還具有主動齒輪軸線可以相對從動齒輪軸線偏移的特點，這一點對于汽車的技術性能非常重要，工程師可以在不改變發(fā)動機的位置尺寸就可以直接改變驅動橋的離地間隙，也就是改變整部車的離地間隙。
有些汽車在同一車架上生產轎車和運動休閑車，其底盤的參數(shù)變換也是利用了雙曲線齒輪這一特性。由于有這些優(yōu)點，目前汽車的驅動橋已經趨向于用雙曲線齒輪，實際上近年進口汽車基本上是采用雙曲線齒輪，國產汽車也有許多車型采用雙曲線齒輪，并已經越來越多地在中、重型貨車上得到采用。
但雙曲線齒輪工作時，齒面間會有較大的相對滑動，且齒面壓力很大，齒面油膜容易被破壞。為減少摩擦，提高效率，必須要采用含有防刮傷添加劑的專用雙曲線齒輪油，絕不能用其它的齒輪油代替，否則將使齒面迅速磨損和擦傷，嚴重影響汽車的運行狀態(tài)。
未來發(fā)展
世界各汽車制造商都在對傳統(tǒng)汽車技術進行重大改進。如果中國的汽車企業(yè)不在汽車傳統(tǒng)傳動系統(tǒng)研究上付出相應的努力，將有落后于世界其他汽車企業(yè)的危險。中國的汽車工業(yè)應與其合資伙伴進行或做，加強發(fā)展改良的柴油發(fā)動機和火花點火技術。研究人員也應把重點放在先進的汽油和柴油發(fā)動機技術、超低排放汽油發(fā)動機系統(tǒng)、柴油機微粒過濾器、去氮氧化物催化劑、選擇催化還原（SCR），以及改進的機內燃燒控制系統(tǒng)上。汽車工業(yè)必須設法模擬汽車傳動系統(tǒng)的能力，以便優(yōu)化整體性能，包括燃料經濟性、排放及車輛的駕駛性能。未來汽車的深層次發(fā)展將由已經存在和正在緩慢提高的需求和額外的附加要求以及為滿足這些要求所需技術方面的可能性來決定。接下來關于發(fā)展和研究成果方面將成為人們的焦點。汽車業(yè)通過在各項傳統(tǒng)功能如：性能，燃油經濟性，環(huán)境影響，安全，舒適，可靠性方面對產品改進而得到進一步發(fā)展。
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