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車輛與動力工程學院畢業(yè)設計說明書 I 3 噸柴油動力貨車設計（后驅動橋與后懸架設計） 摘要 驅動橋是將傳動軸傳來的扭矩進行減速增扭，并改變其扭矩的方向，再分配 給左右車輪，并使左右車輪具有差速作用，以保證內外車輪以不同的轉速轉向。 懸架是現(xiàn)代汽車上的重要總成之一,它用來感知不同地面給車架的不同程度的， 方向上的力，并利用機構中的彈簧來減小路面的崎嶇不平對乘客乘坐舒適感的影 響。 這次設計從驅動橋開始，首先是對驅動橋的總體認識，根據(jù)設計要求對驅動 橋的形式進行選擇。然后是對主減速器的設計計算，包括對主減速器的概述，形 式的選擇，主減速器齒輪參數(shù)的設計計算，主減速比及載荷的確定，差速器的選 擇，半軸和行星齒輪的參數(shù)計算，半軸的計算，選擇以及對上述各個部分的強度 校核計算。對懸架的設計參考了多種車型，選擇鋼板彈簧非獨立懸架，內容包括 懸架形式的選擇，鋼板和減震器的計算等。 懸架的作用是傳遞車架（承載式車身）和車橋之間一切力和力矩。這次設計 采用非獨立懸架。 設計的重點是對主減速器的齒輪進行設計和計算。懸架方面，鋼板彈簧的選 擇和剛度校核是關鍵。對于各個軸和齒輪的接觸和彎曲強度校核都符合要求。 關鍵詞：驅動橋，主減速器，半軸，鋼板彈簧 車輛與動力工程學院畢業(yè)設計說明書 II 3T DIESEL FUEL POWER TRUCK DESIGN（REAR DRIVING AXLE AND REAR SUSPENSIONASSEMBLY) ABSTRACT Driving axle works that transmission shaft brought over torque proceed deceleration speed increased，combine transfer his tensional heading，reassign given about left and right wheel. combine gotten about possess differential acting ， withal guarantee wheel inside and outside and withal different rotation rate turn，The suspension system is the important part of the morden automotive, the suspension system feel much power of the frame from the road surface, sping in the system absorb the shocks of all kinds of the road surface, so that passengers have a comfortable ride. The design starts from the live axle ，first I know about type， It joins up handgrip carriage and axletree elastically. primary mission yes transfer action at wheel and carriage of compartment wholeness force and moment；relax pavement hand down to carriage shock load， attenuation resulting bearing systemic vibrate，guaranee garage gotten smoothness；guarantee wheel at pavement dissatisfaction and load fluctuation hour in the right would motility， The function of the suspension transfers all of force and moment between the frame ( bearing the weight of the body )and the axletree. This design adhibits the disindependencing suspension. The key of the design designs and calculate to gear wheel of the main reducing gear， The crux is the way of rear suspension,siderography selecting and rigidity.osculation intension Structure simplicity, usability best, adjust service easiness. KEY WORDS: driving axle，main reducing gear, semi axis, plate spring 車輛與動力工程學院畢業(yè)設計說明書 III 符號說明 rr: 車輪的滾動半徑 np: 最大功率時發(fā)動機的轉速 vamax: 最高車速 igH: 變速器最高檔傳動比 Temax: 發(fā)動機最大轉矩 N: 驅動橋數(shù)目 iTL: 由發(fā)動機至所計算的主減速器從動齒輪之間的傳系最檔傳動比 T：上述傳動部分傳動效率 K0：離合器產生沖擊載荷時超載系數(shù) G2: 滿載時一個驅動輪上的靜載荷系數(shù) : 輪胎與路面間的附著系數(shù) rr: 車輪的滾動半徑 lB : 所計算的主減速器從動齒輪到驅動車輪之間的傳動效率 ilB : 所計算的主減速器從動齒輪到驅動車輪之間的傳動比 p：單位齒長上的圓周力 N/mm ig：變速器檔傳動比 d1：主動齒輪節(jié)圓直徑 F：動齒輪的齒面寬 : 半軸的扭轉應力 T ：半軸的計算轉矩 d：半軸桿部直徑 K ：超載系數(shù) Ks：尺寸系數(shù)，反映材料性質的不均勻性，與齒輪尺寸及熱處理等有關。 Km：載荷分配系數(shù) Kv： 質 量 系 數(shù) ， 對 于 汽 車 驅 動 橋 齒 輪 ， 當 齒 輪 接 觸 良 好 、 周 節(jié) 及 徑 向 跳 動 精 度 高 時 車輛與動力工程學院畢業(yè)設計說明書 IV 目 錄 第一章 前言............................................1 第二章 驅動橋結構方案分析..............................2 2.1 驅動橋概述......................................2 2.2 驅動橋形式及選擇................................3 第三章 主減速器設計.....................................4 3.1 主減速器結構方案分析............................4 3.2 主減速比及計算載荷的確定.......................4 3.2.1 主減速比 的確定............................40 3.2.2 齒輪計算載荷的確定... .....................4 3.3 主減速器齒輪主要參數(shù)計算........................5 3.3.1 主、從動齒輪齒數(shù)的選擇..................6 3.3.2 從動齒輪節(jié)圓直徑及端面模數(shù)的選擇...........6 3.3.3 齒面寬的選擇 ...........................7 3.3.4 雙曲面齒輪的偏移距.....................7 3.3.5 螺旋角的選擇............................7 3.3.6 圓弧齒雙曲面齒輪的幾何尺寸設計..........8 3.4 主減速器齒輪強度計算.........................18 3.4.1 單位齒上的圓周力..........................18 3.4.2 齒輪彎曲強度計算..........................19 3.4.3 齒輪接觸強度計算..........................20 3.5 主減速器的材料和熱處理......................21 3.6 主減速器錐齒輪軸承的載荷計算...................22 3.6.1 主減速器主動錐齒輪上的當量轉矩 的計算...221dT 3.6.2 主減速器主動錐齒輪齒面寬中點處圓周力計算.22 3.6.3 雙曲面齒輪的軸向力與徑向力的計算........22 3.6.4 懸臂式支承主動錐齒輪的軸承徑向載荷的確定.23 3.6.5 主減速器從動錐齒輪的軸承計算.............25 第四章 差速器設計......................................27 4.1 差速器結構方案分析...........................27 車輛與動力工程學院畢業(yè)設計說明書 V 4.2 差速器齒輪主要參數(shù)計算.......................28 4.3 差速器齒輪強度計算...........................31 第五章 半軸及橋殼設計..................................33 5.1 半軸的設計計算. ................................33 5.1.1 半軸的形式.................................33 5.1.2 半軸參數(shù)計算...............................33 5.1.3 半軸的強度計算.............................30 5.2 半軸的結構、材料與熱處理........................35 5.3 橋殼的設計計算.................................35 5.3.1 橋殼的設計.................................35 5.3.2 橋殼強度計算...............................36 第六章 后懸架設計......................................33 6.1 后懸架概述.....................................33 6.2 后懸架的設計計算...............................35 6.2.1 懸架已知參數(shù)...............................39 6.2.2 懸架主要參數(shù)的確定.........................40 6.2.3 彈性元件的設計計算.........................40 6.2.4 后鋼板彈簧的計算.......................43 第七章 結論...........................................49 參考文獻...............................................50 致謝...................................................51 外文資料譯文
燃料汽車電子設備
隨著油價的不斷上漲，汽車制造商們正在重新設計發(fā)動機管理系統(tǒng)，以適應燃料中乙醇用量不斷增加的趨勢。
世界原油產量預計將在2010－2020年之間達到頂峰，期間，原油的消耗量將比新探明儲量更重要，原油價格也將會不停的上漲，交通業(yè)是耗油大戶，隨著油價的上漲，汽車必須提高燃油利用率。
汽車同時也是最大的污染源，在法規(guī)的約束下，交通運輸所帶來的污染已經得到了有效地改善，特別是鉛和一氧化碳的排放量明顯降低了。然而，一些長期的污染問題仍待解決，特別是以二氧化碳為代表的溫室氣體排放。
為了在競爭中生存，汽車制造商們正在研究能降低油耗或減少廢氣排放的新技術和代用燃料，作為一種代用燃料，乙醇憑借其靈活的使用方式，越來越多的受到青睞。駕駛員可以在標準的汽油和乙醇之間靈活的選擇。
“發(fā)動機管理系統(tǒng)對于這種柔性燃料系統(tǒng)來說是必不可少的?！狈▏谭ɡ讑W稱，“改系統(tǒng)可以控制扭矩、輔助系統(tǒng)、診斷故障、更重要的是，他能控制廢氣排放?！?
扭矩控制功能可根據(jù)駕駛員需要的操縱性和加速能力調控發(fā)動機的輸出扭矩、發(fā)動機扭矩控制功能還可以和其他一些功能，如牽引力控制、巡航控制、變速器和制動器等相互配合。
尾氣排放主要分為3類：排氣管排放、加油時產生的排放和蒸發(fā)性排放，要解決為期排放所帶來的問題，關鍵是要符合尾氣排放標準，同時盡量降低油耗。這兩點可以通過專用后處理裝置，如催化轉換器、傳感器和機電執(zhí)行機構來實現(xiàn)。
發(fā)動機管理系統(tǒng)控制扭矩和排放的方式很復雜，進入發(fā)動機的空氣和再循環(huán)廢氣通過專用的傳感器和執(zhí)行機構實現(xiàn)精確的定量控制，首先噴入適量的燃油，以實現(xiàn)最能發(fā)揮催化劑效率的最佳空\燃比，接著適時點燃混合氣，三元催化會最終使廢氣排放保持在可接受的水平上。
所有這些功能需要通過數(shù)據(jù)總線和導線的連接與其它電子裝置相互配合。通過這些裝置發(fā)回的反饋信息，發(fā)動機管理系統(tǒng)可以屏蔽無關的干擾和變化。
提高燃油利用率和減少溫室氣體排放可通過采用發(fā)動機技術或使用不同的燃料來實現(xiàn)。至于哪種方法更好，這要取決于成本、市場接受度以及政治和財政上的刺激等因素。
例如，使用E85燃料，即含85％乙醇和15％汽油的混合燃料的汽車，其排放量只有單純使用汽油時的79％，乙醇之所以成為廣受歡迎的代用燃料，主要是因為它的含碳量比汽油少，所以燃燒時產生的廢氣也相對較少。
與使用汽油的車相比，大部分使用酒精的車一氧化碳和二氧化碳排放量更低、烷烴或非烷烴碳氫排放量相等或更低，使用乙醇和汽油的汽車所產生的氮氧化物排放量大致相同，因為乙醇燃料的高揮發(fā)性成分含量比汽油低，所以蒸發(fā)性排放量也較低。
此外，乙醇可以用農作物來生產，因此是一種可再生燃料，生物乙醇實際上不產生任何來自化石的二氧化碳，也就是說，二氧化碳的凈增加值為零 。
減少汽車排放量的潛力是巨大的，但如果完全依賴生物燃料，則需要大量的種植面積，因此在今后的一段時間里，乙醇的市場占有率與原油相比仍將十分有限，如果汽車能在兩種燃料之間靈活選擇，那么用乙醇做燃料仍不失為一種緩解石油危機的有效方法。
與傳統(tǒng)汽車發(fā)動機相比，裝有柔性燃料發(fā)動機管理系統(tǒng)的發(fā)動機在不增加成本的情況下，可以在普通無鉛汽油和含酒精0到100％的混合燃料之間任意轉換，正是因其幾乎不需要增加額外成本，該技術在農業(yè)資源富庶的國家尤其受歡迎。
然而，對原有發(fā)動機進行一些改裝還是必要的。汽油發(fā)動機上使用的某些材料和酒精是完全不相容的。“燃料的腐蝕性和揮發(fā)性是對零部件影響最大的兩個因素，”法雷奧公司稱，“因此需要對油泵、燃油管路、油箱和噴油器的材料和設計進行更改。”
但是并沒有必要為乙醇特制熱導傳感器。乙醇的理論空/燃比與汽油相差很大，例如E100為9:1,E85為10:1,3而汽油則為14.7:1，因此，可以用汽油機上已有的標準氧化傳感器來確定酒精和汽油的含量。
盡管從加油泵中流出的混合燃料的酒精含量是一定的，但油箱里的酒精含量可能會不一樣，因為加入的燃料可能會和油箱中原來剩余的燃料混合在一起，這就需要發(fā)動機管理系統(tǒng)根據(jù)汽車的實際情況進行調整，以保證最佳的運轉效果。
相同體積的乙醇所含的能量比汽油大約低30％，燃料消耗也相應的比汽油機高30％，為了解決效率降低的問題，汽車制造商們將油箱的容積相應增大，這樣汽車的行駛里程就不會因此降低，噴油器的流量范圍也必須相應的增大。
由于乙醇中含有的高揮發(fā)性物質比汽油少，因此可能會因發(fā)冷起動問題，解決這一問題有兩個方法：在美國和瑞典，混合燃料中至少含有一定量的汽油，冬季的汽油含量可高達30％，在瑞典，冬天常常需要在－10℃的低溫下起動，為此，車輛都備有一種電熱裝置為汽車保溫。
在巴西，人們用純酒精作燃料，不過在車上要另加一個小型的備用汽油油箱，并且專門為冷起動增加一套燃油管。同時也可以通過改進啟動器來增加起動時的轉速。
巴西產的柔性燃料汽車上，發(fā)動機管理系統(tǒng)必須控制來自冷起動油箱的輸入信號，并且在該油箱油量過低時能夠察覺；系統(tǒng)的輸出信號必須能通過電控汽油泵繼電器和冷起動噴油電磁閥，控制冷起動的供油量。
這種車上還可以選裝顯示設備，包括顯示所用燃料和冷啟動油箱位過低的指示器。這些功能用標準汽油機ECU進行重新設計。
在寒冷天氣里，發(fā)動機管理系統(tǒng)在啟動專用的電控泵和電磁閥的同時，用汽油進行“全組壁濕預噴”。一旦發(fā)動機達到足夠快的轉速，噴油器就會開始噴射乙醇。因此，汽油噴射在幾秒鐘之內就會停止。
發(fā)動機管理系統(tǒng)是怎么知道燃油的混合比的？不是靠不斷的測量混合氣的濃度，而是通過標準的上游氧傳感器來確定酒精和汽油的量。該傳感器可測出實現(xiàn)最佳催化率所需的空然比和實際空燃比的差。
“微小的誤差可通過用于噴油正時的‘A反饋’校正法直接消除，誤差很大時，則說明燃料的性質發(fā)生了改變。”法雷奧公司稱?！叭缓?，發(fā)動機管理系統(tǒng)會重新對空然比進行估算，并根據(jù)實驗所得的空/ 燃比和汽油/乙醇比之間的對應關系，將其換算為汽油和乙醇的混合比。”
為了增強可靠性，一有跡象表明燃料很可能發(fā)生了改變，發(fā)動機管理系統(tǒng)就會對酒精濃度進行估算。估算的時候采用關于主油箱油位的信息，如果發(fā)動機管理系統(tǒng)能收到這樣的信息的話。
將發(fā)動機所需的扭矩換算為發(fā)動機管理系統(tǒng)所需的空氣、燃料用量和點火時間時，需要考慮實際參數(shù)的變化，如理論空燃比、熱值和燃燒效率等?！皩τ诨旌腿剂希l(fā)動機管理系統(tǒng)的各個參數(shù)和各種行為是通過將估算的乙醇/汽油比作為插值參數(shù)而求出的，”法雷奧公司稱，在計算噴油量和點火提前指時用的是同一參數(shù)。
進氣量也會發(fā)生變化，汽油和乙醇的蒸發(fā)潛熱值相差很大，簡單的說，乙醇會使吸入的空氣因冷卻而密度增加。進入氣缸內的空氣質量隨之增大。為此，校準進氣量時就必須按100%乙醇和100%汽油兩種情況進行。
“據(jù)我們估計，幾年內大部分歐洲和美國汽車都會在燃油中加入乙醇。”法雷奧公司表示，“E85燃料是否會成為標準還很難說，不過我們以為此作好準備?！?
4
fuel electronics
As oil gets more expensive, carmakers are looking at engine management systems that can cope with increasing levels of ethanol.
Oil production could peak between 2010 and 2020.When it happens ,oil consumption will become more important than new discoveries ;and crude oil prices will rise and rise .Transport is the dominant sector in terms of oil use and motor vehicles will have to become more fuel-efficient.
Vehicles are the largest source of pollution. Regulations have addressed the problem for transportation and real improvements have been achieved ,particularly in lead and carbon monoxide levels .But some long-term emissions have not been considered .This is particularly eve case for greenhouse gas emissions ;carbon dioxide in particular.
To protect their livelihoods ,carmakers are investigating technologies and alternative fuels that either reduce oil consumption or cut emissions .Ethanol is starting to become more attractive as it can be used flexibly .The driver can run on standard gasoline or on
The engine management system is an essential part of such systems’ success ,says French Tier One supplier Valeo :“They control
Torque, ancillary systems ,diagnose servicing issues and ,most importantly ,emissions.”
Torque control features deliver engine responses with levels of drivability and acceleration in agreement with users’ requests .Engine torque control also co-prorates functions such as traction control, cruise control, transmissions and brakes.
Emissions break down into three main areas: those from the exhaust tailpipe; refueling losses and evaporative emissions .The issue is to comply with emission regulations and minimize fuel consumption .This is achieved through dedicated after-treatment components such as catalytic converters, sensors and electro-mechanical actuators.
The way the engine management system controls torque and emission is complex .The quantities of air and recycled exhaust gases entering the engine are precisely managed with dedicated sensors and actuators .The right air/fuel mix for the catalyst to work properly .The mix has to ignite at the right time .The three-way catalyst then has to keep final pollutant emissions at acceptable levels.
All these functions need to cooperate with other electronic units through data buses and eventually wired connections .Feedback from them allows the system to ignore any irrelevant disturbances and variations.
Fuel efficient driving and reduction of greenhouse gas emissions can be achieved by using engine technologies or different fuels .Which prevails will depend on cost ,market acceptance ,and political and fiscal incentives.
A vehicle fuelled with E85 fuel ,which contains 85 percent ethanol and 15 percent gasoline ,produces just 79percent of the emissions produced by pure gasoline .The interest in ethanol as an alternative fuel comes mainly from its clean burning qualities .Ethanol contains less carbon than gasoline.
Compared with gasoline, most ethanol cars produce lower carbon monoxide and carbon dioxide emissions and the same or lower levels of hydrocarbon and non-methane hydrocarbon hydro carton emissions Oxides of nitrogen emissions are about the same for ethanol and gasoline vehicles.
Ethanol fuel has fewer highly volatile components than gasoline and so has emissions.
Moreover it can be produced from crops and so qualifies renewable fuel .Bio-ethanol produces no fossil carbon dioxide because the plants used to make ethanol take CO2 out of the air in order to grow . There is a net increase of zero.
There is no need, however, to fit a specific ethanol conductivity sensor .The stoichometric air-fuel ratio of ethanol is very different to gasoline .For E100 it is 9:1, for E85 is it 10:1,for gasoline it is 14.7:1.Because of this ,it is possible to recognize the amount of ethanol and gasoline by using the standard oxygen sensor already found in gasoline architectures.
Although the ethanol content of the blend at a refueling pump is specified ,the content of the vehicle tanks may be different because it may mix with any fuel already in the vehicle’ stank .It is the job of the engine management system to make the adjustments the vehicle needs to operate optimally.
The energetic content of ethanol is around 30 percent less than the same volume of gasoline .Fuel consumption is potentially increased in the same proportion .To deal with the decline in fuel efficiency, carmakers install larger fuel tanks, so the vehicle’s range is not compromised .Injectors’ flow ranges have to be increased too.
Ethanol has fewer highly volatile components than gasoline ,so Cole starting problems may occur .To solve this issue two kinds of solutions ate used ;In the US and Sweden ,a fuel with a minimal amount of gasoline is used ,the amount of gasoline can be as high as 30 percent in the winter .In Sweden ,where cold starts at -10℃ are common in the winter ,the vehicle is plugged in to an electric source to keep it warm.
In Brazil, pure hydrated ethanol is used but with a small additional gasoline reserve tank and fuel line that is used only for cold starts .Starters can also be modified to increase the cranking speed.
In Brazilian flex-fuel vehicle architectures, the engine management system must manage inputs from the cold start tank, recognizing when fuel is low .Its outputs must manage gasoline supply for cold start via an electric gasoline pump relay and a cold-start injection solenoid valve.
Optional driver display information includes indicators to show the type of fuel in use and when the cold start tank is low .These features require hardware that is usually available as spares on standard gasoline ECUs .so no specific ECU has to be designed.
In cold weather ,the engine management system orders a wall-wetting ,full-group pre-injection is performed using gasoline ,by simultaneously activating the dedicated electric pump and the solenoid valve .As soon as the engine speed is high enough the injectors inject the ethanol .Gasoline injection is then phased out within a few seconds.
How does it know that the fuel blend is? Not by constantly measuring the mix .A standard upstream oxygen sensor recognizes the amount of ethanol and gasoline. This sensor measures the difference between the air/fuel ratio required for optimal catalyst efficiency and those effectively achieved.
“Slight errors are directly cancelled with the lambda feedback correction performed on injection timing, while large ones are arreibuted to changes in fuel characteristic.” says Valeo .The new air/fuel ratio is then estimated and translated into gasoline ethanol ratio .This translation is gassed on the experimental relationship between air/fuel and gasoline/ethanol ratios.
To improve robustness, estimating the ethanol ratio is triggered as far as possible by information indicating that it is likely that there has been a fuel change. When available, information on the main tank level is used.
The translation of torque requests into engine management requests for the air, fuel and ignition has to take into account differences in physical parameters such as the stoichometric ratio, calorific power and combustion efficiency. For blend fuels, engine management parameters and behaviors are obtained by using the estimated ethanol/gasoline ratio as an interpolating parameter. Says Valeo .The same is used to calculate injection masses and spark advance values.
Air loads differ too .There are significant differences between gasoline and ethanol’s latent heat vaporization. Roughly speaking ,the ethanol cools down the intake air and thus increases its density .The air mass admitted into the cylinders is higher as a result .Because of this ,air load calibrations have to cater for both 100 percent ethanol and 100 percent gasoline.
“We expect ethanol to be blended with gasoline in most European and US fuel in the next few years,” sys Valeo. “Whether E85 will become the rule is more difficult to say, but we are ready for it.”