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SY-025-BY-2
畢業(yè)設計（論文）任務書
學生姓名
隋震
系部
汽車與交通工程學院
專業(yè)、班級
車輛工程07-1班
指導教師姓名
臧杰
職稱
教授
從事
專業(yè)
汽車運用工程
是否外聘
否
題目名稱
東風EQ1181W型載貨汽車雙片離合器設計
一、設計（論文）目的、意義
離合器是汽車傳動系中的重要部件，它的構造特性與發(fā)展和傳動系統(tǒng)緊密相關。在我國，乘用車中自動擋車款式只占全國平均數(shù)的26.53%；若考慮到商用車中更多數(shù)是采用手動變速器，手動擋汽車目前仍然是世界車款的主流。可以說，從目前到將來離合器這一部件將會伴隨著內燃機一起存在，不可能在汽車上消失。因此研究離合器結構設計有著實際意義。
可以針對東風EQ1181W型自卸車雙片離合器設計的各項參數(shù)，設計雙片離合器。
通過設計掌握汽車螺旋彈簧離合器設計的原則和方法，培養(yǎng)正確的研究方法、理論聯(lián)系實際的工作作風、嚴肅求實的學習態(tài)度。
課題綜合運用了汽車設計、汽車構造、CAD繪圖等知識。
二、設計（論文）內容、技術要求（研究方法）
1、設計內容
（1）離合器壓盤總稱設計、從動盤總成設計、彈簧的參數(shù)、尺寸、材料及結構設計；（2）離合器的裝配及零件CAD工程圖。（3）完成設計說明書。
2、技術要求
（1）通過文獻資料收集，熟悉汽車離合器設計的有關理論知識，研究外離合器設計和汽車計算機輔助設計的發(fā)展狀況。
（2）實地到汽車廠等部門學習調查，了解汽車離合器設計的方法、CAD的使用。
（3）編寫課題研究大綱和開題報告。
（4）針對東風EQ1181W型載貨汽車的各項參數(shù)，計算確定離合器的尺寸。完成相關CAD圖紙。
（5）按進度要求獨立完成畢業(yè)設計，服從指導教師安排；完成的畢業(yè)設計格式規(guī)范；方案選擇合理，具有可行性、經濟型、實用性，設計思路清晰，符合實際，圖紙正確符合制圖標準。內容完整。
三、設計（論文）完成后應提交的成果
說明書1份（1.5萬字以上）
折合零號圖3張
四、設計（論文）進度安排
（1）調研、資料收集，完成開題報告 第4周（3月24日~3月30日）
（2）參數(shù)選擇方案確定，列文稿大綱，設計計算 第5~6周（3月31日~4月13日）
（3）完成設計說明書，完成圖紙繪制 第7~13周（4月14日~6月1日）
（4）交稿，預答辯 第14周（6月2日~6月8日）
（5）設計審核、修改 第15~16周（6月9日~6月22日）
（6）畢業(yè)設計答辯 第17周（6月23日~6月29日）
五、主要參考資料
1、有關汽車設計的科技書：
[1]汽車標準匯編。天津：中國汽車技術研究中心標準研究所，2005.
[2]林世裕主編。膜片彈簧與蝶形彈簧離合器的設計與制造。東南大學出版社，1995
[3]孫蘇榕。計算機輔助產品造型設計。上海：中國紡織大學出版社，2000
2、有關的期刊：
[1]姜彥龍主編，捷達轎車離合器常見故障檢測與檢修[J]。黑龍江科技，2009.09
[2]楊曉輝主編，膜片彈簧分離特性分析與計算[J]。2009.02
[3]司傳勝主編。汽車膜片彈簧離合器的優(yōu)化設計[J]。林業(yè)機械與木工設備，2004，12
[4]羅頌榮主編。汽車拉式膜片彈簧片的優(yōu)化設計[J]。常德師范學院學報，2001.01
六、備注
指導教師簽字：
年 月 日
教研室主任簽字：
年 月 日
SY-025-BY-3
畢業(yè)設計（論文）開題報告
學生姓名
隋 震
系部
汽車與交通工程學院
專業(yè)、班級
車輛工程07-1
指導教師姓名
臧 杰
職稱
教授
從事
專業(yè)
車輛工程
是否外聘
□是■否
題目名稱
東風EQ1181W型載貨汽車雙片離合器設計
一、課題研究現(xiàn)狀、選題目的和意義
離合器總成，也有人稱為壓盤總成。在汽車上，離合器總成被螺栓緊固在發(fā)動機飛輪上。離合器總成用來操控離合器片與飛輪之間分離或磨合。安裝時，離合器彈簧給離合器總成加載，彈簧力將離合器片壓緊在飛輪上。如果駕駛員踏動離合器踏板時，踏動力會傳動到離合器分離軸承，分離軸承將力道傳遞到離合器壓盤上，壓盤使離合器片脫離飛輪摩擦面，這樣離合器片就可以自由旋轉。達到分離目的。
隨著我國自動檔轎車的增加，我國傳統(tǒng)離合器行業(yè)的發(fā)展前景日益擔憂，不少企業(yè)都在尋求新的持續(xù)發(fā)展的途徑。2007年以前，我國汽車產量持續(xù)增長、汽車保有量的增加、出口市場需求的擴張等三大因素推動我國汽車離合器行業(yè)連續(xù)8年快速發(fā)展，2007年我國汽車離合器的產量突破1000萬套。自2008年以來，受全球金融危機影響，中國汽車銷量為938萬輛，增長率僅為6.7%，離合器的市場規(guī)模約為55億元。預計到2010年中國車市將走出低谷，屆時我國離合器總銷售額將有望突破80億元。DCT技術在中國良好的發(fā)展前景，將使我國摩擦片汽車離合器行業(yè)獲得新的發(fā)展機遇。但是，市場競爭也很激烈，長春一東是國內汽車離合器制造行業(yè)龍頭企業(yè)，已形成75萬套的生產力，是國內規(guī)模最大，系列最寬的離合器生產廠家，行業(yè)地位較高。公司在主機配套市場處于龍頭地位，面向全國64家主機廠供貨，占領了國內中重型商用車市場的半壁江山。
目前國內汽車離合器主要是干摩擦式離合器，其中，膜片彈簧離合器和螺旋彈簧離合器的產量比例已達到1：1，隨著時間的推移將會由膜片彈簧離合器取代。膜片彈簧離合器現(xiàn)以推式為主，但拉式以其優(yōu)越的性能，正作為研發(fā)重點，不久亦會面世。上海離合器總廠為通用別克轎車配套的4T65E液力變矩器，是自主開發(fā)成功的典范，而且已建成年產10萬套生產能力。引進技術企業(yè)和中外合資企業(yè)的產品質量和技術水平都達到了國外同類企業(yè)的同期水準。如上海離合器總廠為桑塔納配套的離合器達到了德國F&S公司水準，長春一東離合器股份有限公司為一汽配套的離合器達到了英國AP公司水準，南京法雷奧有限公司為依維柯配套的離合器達到了法國Valeo公司水準等。
在消化吸收引進技術的同時，在行業(yè)協(xié)會的組織下，通過產、學、研相結合，已經建立起我國自己的膜片彈簧離合器設計理論，有力支撐了離合器開發(fā)；雙質量飛輪減振器的設計理論、液力變扭器的設計理論也已建立，有的企業(yè)已建立起相當實力的技術中心。有8家企業(yè)具備與國外同行相似的制造膜片彈簧離合器的關鍵熱處理先進設備和工藝。拉式膜片彈簧離合器、雙質量飛輪減振器、液力變扭器和大直徑膜片彈簧離合器的開發(fā)研制已經取得成功。如上海離合器總廠自行開發(fā)研制的液力變矩器已為上海通用別克轎車配套。
經過多年的實踐經驗使人們逐漸趨向于采用單片干式摩擦離合器。它具有從動部分轉動慣量小，散熱性好，結構簡單，調整方便，尺寸緊湊，分離徹底等優(yōu)點。而且只要在結構上采取一定措施，也能使其接合平順。因此，它得到了極為廣泛的應用。
如今，單片干式摩擦離合器在結構設計方面也相當完善：采用具有軸向彈性的從動盤，提高了離合器的接合平順性；離合器中裝有扭轉減振器，防止了傳動系統(tǒng)的共振，減少了噪音；以及采用了摩擦較小的分離桿機構等。另外，采用了膜片彈簧作為壓簧，可同時兼起到分離杠桿的作用，使離合器結構大為簡化，并顯著地縮短了離合器的軸向尺寸。膜片彈簧和壓盤的環(huán)行接觸，可保證壓盤上的壓力均勻。由于膜片彈簧本身的特性，當摩擦片磨損時，彈簧的壓力幾乎沒有改變，且可減輕分離離合器時所需要的踏板力。為了提高離合器的傳扭能力，在重型汽車上多采用多片干式離合器。次外，近年來由于多片濕式離合器在技術上的不段改善，在國外的某些重型牽引汽車和自卸車上又開始采用多片濕式離合器，并有不斷增加的傾向。與干式離合器相比，由于用油泵進行強制制冷的結果，摩擦表面的溫度較低（不超過 93℃）。因此，允許起步時長時間地打滑或用高檔起步而不致燒損摩擦片，具有良好的起步能力。據(jù)說這種離合器的使用壽命可達干式離合器的五、六倍。
為了實現(xiàn)離合器的自動操縱，有自動離合器。采用自動離合器時可以省去離合器踏板，實現(xiàn)汽車的“雙踏板”操縱。與其他自動傳動系統(tǒng)（如液力傳動）相比，它具有結構簡單，成本低廉及傳動效率高的優(yōu)點。因此，在歐洲小排量汽車上曾得到廣泛的應用。但是在現(xiàn)有自動離合器的各種結構中，離合器的摩擦力矩的力矩調節(jié)特性還不夠理想，使用性能不盡完善。例如，汽車以高檔低速上坡時，離合器往往容易打滑。因此必須提前換如低檔以防止摩擦片的早期磨損以至燒壞。這些都需要進一步改善。
對于重型離合器，由于商用車趨于大型化，發(fā)動機功率不斷加大，但離合器允許加大尺寸的空間有限，離合器的使用條件日酷一日，增加離合器傳扭能力，提高使用壽命，簡化操作，已成為重型離合器當前的發(fā)展趨勢。為了提高離合器的傳扭能力，在重型汽車上可采用雙片干式離合器。從理論上講，在相同的徑向尺寸下，雙片離合器的傳扭能力和使用壽命是單片的2倍。但受到其他客觀因素的影響，實際的效果要比理論值低一些。
近年來濕式離合器在技術上不斷改進，在國外某些重型車上又開始采用多片濕式離合器。與干式離合器相比，由于用油泵進行強制冷卻的結果，摩擦表面溫度較低(不超過93℃)，因此，起步時長時間打滑也不致燒損摩擦片。查閱國內外資料獲知，這種離合器的使用壽命可達干式離合器的5-6倍，但濕式離合器優(yōu)點的發(fā)揮是一定要在某溫度范圍內才能實現(xiàn)的，超過這一溫度范圍將起負面效應。目前此技術尚不夠完善。對于以內燃機為動力的汽車，離合器在機械傳動系中是作為一個獨立的總成而存在的，它是汽車傳動系中直接與發(fā)動機相連接的總成。雖然自動傳動系統(tǒng)是汽車傳動系的發(fā)展趨勢，但手動式仍然占多數(shù)，目前來說手動當汽車仍是主流，而且就駕駛者的個人需求而言，手動擋也必然不會消失。故而研究離合器是有必要有實際意義的。
本次設計的課題是東風EQ1181W型載貨汽車的各項參數(shù)，設計雙片離合器。在該款車型上雙片離合器相較于單片離合器，有著傳遞轉矩的能力較大；結合更為平順、柔和；在傳遞相同轉矩的情況下，徑向尺寸較小的優(yōu)點。按時雙片離合器本身卻有著種種不足，比如易引起摩擦片過熱，加快其磨損甚至燒壞；分離行程大，不易分離徹底等。本次設計將著重解決此類問題。
二、設計（論文）的基本內容、擬解決的主要問題
1、掌握汽車離合器結構及工作原理。
離合器位于發(fā)動機和變速箱之間的飛輪殼內，用螺釘將離合器總成固定在飛輪的后平面上，離合器的輸出軸就是變速箱的輸入軸。
本次設計的課題為雙片離合器，是采用雙摩擦片的摩擦離合器
2、 離合器壓盤總成設計、從動盤總成設計、彈簧的參數(shù)、尺寸、材料及結構設計
3、 使用AutoCAD完成工程圖紙
4、 編寫設計說明書
5、 你解決的主要問題：
雙片離合器方案精心選擇，確定基本參數(shù)摩擦片外徑D及后備系數(shù)β。
從動機構尺寸計算與校核，從動盤尺寸計算與校核。
主動部分中壓盤傳力方式選擇，幾何尺寸確定，材料選擇。
螺旋彈簧尺寸計算與校核。
三、技術路線（研究方法）
針對東風EQ1181W車型的具體參數(shù)，從網絡、教材、書刊、論文等方面搜集資料，確定相關參數(shù)，進行計算、校核。聯(lián)系生產廠家，針對該型號離合器研究實際生產尺寸及工藝。以理論聯(lián)系實際，比較設計課題與實際應用中的不同，進行相應改進。使設計課題具有實際意義。
離合器蓋的設計
壓盤設計
確定主要零部件主要結構尺寸、參數(shù)選擇和計算。圓柱螺旋彈簧設計
從動盤轂設計
從動片設計
扭轉減震器設計
摩擦片設計
從動盤總成設計
基本尺寸參數(shù)選擇
主動部分設計
四、進度安排
（1）調研、資料收集，完成開題報告 第4周（3月24日~3月30日）
（2）參數(shù)選擇方案確定，列文稿大綱，設計計算 第5~6周（3月31日~4月13日）
（3）完成設計說明書，完成圖紙繪制 第7~13周（4月14日~6月1日）
（4）交稿，預答辯 第14周（6月2日~6月8日）
（5）設計審核、修改 第15~16周（6月9日~6月22日）
（6）畢業(yè)設計答辯 第17周（6月23日~6月29日）
五、參考文獻
[1]臧杰，閻巖.汽車構造.北京:機械工業(yè)出版社,2005
[2]劉惟信. 汽車設計.北京:清華大學出版社,2001
[3]馮海辰,王宜君.離合器軸的淬火工藝，機械研究與應用 , Mechanical Research & Application, 編輯部郵箱 2007年 01期??
[4]《汽車工程手冊》編輯委員會.汽車工程手冊.設計篇北京：人民交通出版社，2001
[5]《汽車工程手冊》編輯委員會.汽車工程手冊.制造篇北京：人民交通出版社，2001
[6]余志生.汽車理論.第3版.北京：機械工業(yè)出版社,2000
[7]吳君棋等.離合器從動盤轂疲勞分析及優(yōu)化，【J】.機電工程，2009
[8]李濤.轎車離合器膜片彈簧的優(yōu)化設計【J】.科技創(chuàng)新報，2009
[9]姜彥龍.捷達轎車離合器常見故障檢測與檢修【J】.黑龍江科技，2009
[10]楊曉輝.膜片彈簧分離特性分析與計算【J】.2009
[11]司傳勝.汽車膜片彈簧離合器的優(yōu)化設計【J】.林業(yè)機械與木工設備，2004
[12]胡宏偉.濕式自動離合器接合過程特性的研究.浙江大學，2008
[13]秦松濤.汽車離合器摩擦磨損性能及機理研究【J】.裝備制造，2009
[14]顧曉陽.現(xiàn)代設計技術在汽車離合器行業(yè)研發(fā)中的應用【J】.汽車與配件，2007
[15]張衛(wèi)波.汽車膜片彈簧離合器智能優(yōu)化設計技術研究【J】.中國工程機械學報，2007
[16]GU Yanchun YIN Chengliang ZHANG Jianwu. OPTIMAL TORQUE CONTROL STRATEGY FOR PARALLEL HYBRID ELECTRIC VEHICLE WITH AUTOMATIC MECHANICALTRANSMISSION【J】.School of Mechanical Engineering; Shanghai Jiaotong University; Shanghai 200030; China,2007
[17]PENG Yu-xing1; ZHU Zhen-cai1; CHEN Guo-an2 1School of Mechanical and Electrical Engineering; China University of Mining & Technology; Xuzhou; Jiangsu 221008.Theoretical analysis of thermoviscoelastic contact between friction lining and wire rope in mine friction hoists【J】. China 2PLA Engineer Command College; Xuzhou; Jiangsu 221004; China,2009
六、備注：
指導教師意見：
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黑龍江工程學院本科生畢業(yè)設計
附 錄
The basic mechanisms Of Automobiles
The automobile industry is a fast developing industry. From the later 18th century when the first automobile was put on road, this industry has developed tremendously. Now there are thousands of factories all over the world manufacturing.
numerous types of automobiles. This industry employs crores of men and women directly and indirectly in allied industries. The automobile engines are also being used
in engine powered machines for agriculture, construction and manufacturing processes. Various types of small engines are also being used in lawn movers, power.
saws, snow removers and similar equipment. The automobile industry is a developing
and demanding industry which does not find its end or saturation point. There is a great demand for varied types of automotive products, vehicles and engines.
There is also a great demand for trained and experienced persons in this industry for diagnosing motor vehicle troubles, repairing and replacing engines components, transmissions, propeller shafts, differentials, axles, steering system components,brake system components, suspension components, air-conditioners, heaters, body and glass work.
The automobile consists of five basic mechanisms, or components. These are :
(1) The engine, which is the source of power, including the fuel, lubricating,
cooling, and electric systems.
(2) The frame, which supports the engine, wheels, steering and brake systems
and body
(3)The power train, which carries the power from the engine(through the clutch,transmission, drive shaft, differential, and axles)to the car wheels.
(4) The car body .
(5)car-body accessories, including heater ,lights, windshield wipers, and so for
The engine is the source of power that makes the car move. It is usually called an internal combustion engine because gasoline is burned inside the engine cylinders, or combustion chambers. This is in contrast to external-combustion engines(such as steam engines),where the combustion takes place outside the engine. The burning of gasoline in the engine cylinders produces the power. The power is then carried from the engine through the power train to the car wheels so that the wheels turn and the car moves.
The fuel system plays a vital part in the power producing process since it supplies the gasoline to the engine cylinders. In each engine cylinder, a mixture of gasoline vapor and air enters the cylinder, the piston pushes up into the cylinder to compress the mixture, and then an electric spark ignites the compressed mixture so that the piston is forced downward. Of course, in the engine the piston is not blown completely out of the cylinder, the piston simply moves up and down in the cylinder-up to compress as the mixture burns. The piston straight-line motion must be changed to rotary motion before it can be used to make the car wheels rotate. A connecting rod and a crank on the engine crankshaft make this change.
The engine valves get the burned gasoline vapor out of the engine cylinder and bringing fresh changes of gasoline vapor and air into the cylinder. There are two openings ,or ports, in the enclosed end of the cylinder ,each containing a valve. The valve are accurately machined plugs on long stems. When they are closed, or seated (that is, moved up into the ports), the ports are sealed off and gas cannot pass through the ports. When the valve is open, gas can pass through the port
The valves are opened by cams on the engine camshaft. The cam has a high point,r lobe; every time the cam rotates, the lobe comes around under the valve lifter and move it upward. The lifter then carries this upward movement through the pushrod to the rocker arm. The rocker arm pivots on its support and pushes down on the valve stem, causing the valve to move down, that is, to open. After the cam has turned enough to move the lobe out from under the lifter, the heavy valve spring pulls the valve back into its seat. The spring is attached to the upper end of the valve stem by a spring retainer and lock. There is a cam for each valve (two cams per cylinder) on the engine camshaft. The camshaft is driven off the crankshaft by gears or by sprockets and a chain.
When the entire cycle of events requires four piston strokes (two crankshaft revolutions), the engine is called a four-stroke-cycle engine, or a four-cycle engine. The our strokes are intake, compression, power, and exhaust.
On the intake stroke, the intake valve is open. The piston moves down, pulled by the rotation of the crankshaft. This piston movement creates a partial vacuum in the cylinder, and air rushes into the cylinder past the intake valve to "fill up" this vacuum. As the air moves toward the cylinder, it must pass through the carburetor. There it is charged with gasoline vapor. Thus, it is a mixture of air and gasoline vapor that rushes into the cylinder as the piston moves down on theintake stroke.
After the piston moves down to the bottom dead center on the intake stroke, the intake valve closes. The lobe on the cam controlling the intake valve has moved out from under the valve lifter. Since the other valve is also closed, the upper end of the cylinder is sealed. Now, as the piston is pushed up by the rotating crankshaft, the mixture of air and gasoline vapor that has been drawn into the cylinder is compressed. By the time the piston has moved up to the top dead center, the mixture is compressed to a seventh or an eighth of its original volume. That is like taking a gallon of air and compressing it to a pint. The result is high pressure in the cylinder.
About the time the piston reaches the top dead center on the compression stroke, an electric spark occurs at the cylinder spark plug. The spark plug is essentially two heavy wire electrodes; the spark jumps between these electrodes. The spark is produced by the ignition system. It ignites, or sets fire to, the compressed air-gasoline-vapor mixture. Rapid combustion takes place; high temperatures and pressures result. At this instant, the downward pressure on the top of the piston may amount to as much as 2tons. This powerful push forces the piston down, and a power impulse is transmitted to the crankshaft through connecting rod and the crank.
The piston is forced down by the pressure of the burning gasoline vapor during the power stroke. When the piston reaches the bottom dead center, the exhaust valve opens. Now, as the piston starts back up again, it forces the burned gases from the cylinder. By the time the piston has reached the top dead center the cylinder is cleared of the burned gases. The exhaust valve closes and the intake valve opens. Then ,the piston starts back down again on the next intake stroke. The four cycles, or piston strokes, are continuously repeated while the engine is running.
A clutch is a friction device used to connect and disconnect a driving force from a driven member. In automotive application, it is used in conjunction with an engine flywheel to provide smooth engagement and disengagement of the engine and manual transmission.
Since an internal combustion engine develops little power or torque at low rpm, it must gain speed before it will move the vehicle. However, if a rapidly rotating engine is suddenly connected to the drive line of a stationary vehicle, a violent shock will result.
So gradual application of load, along with some slowing of engine speed, is needed to provide reasonable and comfortable starts. In vehicles equipped with a manual transmission, this is accomplished by means of a mechanical clutch.
The clutch utilizes friction for its operation. The main parts of the clutch are a pressure plate, and a driven disk. The pressure plate is coupled with the flywheel, while the driven disk is fitted to the transmission input shaft. The pressure plate is pressed to the disk by the springs so that the torque is transmitted owing to friction forces from the engine to the input shaft of the transmission. Smooth engagement is ensured by slipping of the disk before a full pressure is applied.
The automobiles are equipped with a dry spring-loaded clutch. The clutch is termed "dry" because the surfaces of the pressure plate and driven disks are dry incontrast to oil-bath clutches in which the plate and disks operate in a bath of oil. It is called "spring-loaded" because the pressure plate and the driven disk are always pressed to each other by springs and are released only for a time to shift gears or to brake the automobile.
In addition to the plate and disk, the clutch includes a cover, release levers, a release yoke, pressure springs and a control linkage. The clutch cover is a steel stamping bolted to the flywheel. The release levers are secured inside the cover on the supporting bolts. The outer ends of the release levers are articulated to the pressure plate. Such a construction allows the pressure plate to approach the cover or move away from it, all the time rotating with the flywheel. The springs spaced around the circumference between the pressure plate and the clutch cover clamp the driven disk between the pressure plate and the flywheel.
The springs are installed with the aid of projections and sockets provided on the cover and pressure plate. The pressure plate sockets have thermal-insulation gaskets for protecting the springs against overheating.
The clutch release mechanism can be operated either mechanically or hydraulically. The mechanically-operated release mechanism consists of a pedal,a return spring, a shaft with lever, a rod, a release yoke lever, a release yoke, a release ball bearing with support and a clutch release spring. When the clutch pedalis depressed, the rod and shaft with yoke shift the released bearing and support assembly. The release bearing presses the inner ends of the release levers, the pressure plate is moved away from, the driven disk and the clutch is disengaged. To engage the clutch, the pedal is released, the release bearing thus releasing the release levers so that the pressure plate is forced by its springs towards the flywheel to clamp the driven disk and engage the clutch.
The clutch hydraulically-operated release mechanism consists of a clutch pedal, clutch release spring, a main cylinder, a pneumatic booster, pipelines and hoses and a lever of the clutch release yoke shaft. The main cylinder accommodates a piston with a cup. The pneumatic booster serves to decrease the pedal force required to disengage the clutch. The booster includes two housings with the servo diaphragm clamped in between. The housing accommodates pneumatic, hydraulic and servo plungers. When the clutch pedal is pushed, the fluid pressure from the main cylinder is transmitted through the pipelines and hoses to the hydraulic and servo plungers of the pneumatic booster.
The servo arrangement is intended for automatic change of the air pressure in the pneumatic cylinder proportionally to the force applied to the pedal. The plunger moves with the diaphragm, the outlet valve closes and the inlet valve opens thus admitting the compressed air to the pneumatic plunger piston. The forces created by the pneumatic and hydraulic plungers are added together and are applied through the push rod to the release yoke shaft lever, the lever turns the shaft and the release yoke shaft disengaging the clutch. After the clutch pedal is released,the outlet valve opens and the inlet closes. Under the action of the springs thepistons return the plungers to the initial position and the air from the cylinder is let out to the atmosphere.
Automatic clutches were used in certain U.S. and European cars. American Motors"E-stick" clutch eliminated the need for physical operation of the clutch pedal. A German car maker engineered an automatic clutch system called "Hydrak", which consisted of a fluid flywheel connected to a single, dry disk clutch.
In the "E-Stick" set up, the pressure plate levers "engage" the clutch disk rather than "release" them. Also, the clutch remains disengaged until a servo unit is applied by oil pressure when the shift lever is placed "in gear" with the engine running.
The "Hydrak" unit also begins operation when the lever is "in gear". This activates a booster unit, which disengages the clutch disk. The hydraulic clutch parts are bridged over by a free-wheel unit, which goes into action when the speed of the rear wheels is higher than the speed of the engine. A special device controls ingagement of the mechanical clutch, depending on whether the rear axle is in traction or is pushed by car momentum.
A more-or-less unusual clutch pressure plate set-up is used on late model Chrysler and American Motors cars. Called a semi-centrifugal clutch, the pressure plate has six cylindrical rollers which move outward under centrifugal force until they contact the cover. As engine speed increases, the rollers wedge themselves between the pressure plate and cover so that the faster the clutch rotates, the greater the pressure exerted on the pressure plate and disk.
A transmission is a speed and power changing device installed at some point between the engine and driving wheel of the vehicle. It provides a means for changing the ratio between engine rpm ( revol utions per minute) and driving wheels rpm to best meet each particular driving situation.
Given a level road ,an automobile without a transmission could be made to move by accelerating the engine and engaging the clutch. However, a start under these conditions would be slow, noisy and uncomfortable. In addition, it would place a tremendous strain on the engine and driving parts of the automobile.
So in order to get smooth starts and have power to pass and climb hills, a power ratio must be provided to multiply the torque and turning effort of the engine. Also required is a speed ratio to avoid the need for extremely high engine rpm at high road speeds. The transmission is geared to perform these functions.
The transmission is designed for changing the torque transmitted from the engine crankshaft to the propeller shaft, reversing the vehicle movement and disengaging the engine from the drive line for a long time at parking or coasting. A higher to rque should be applied to the wheels to set an automobile in motion or move uphill with a full load than to keep it rolling after it gets under way on level stretches of the road, when inertia is high and tractive resistance is low. To meet these variable torque requirements, special gear boxes are used. Such gear boxes are called fixed-ratio transmissions.
In a gear train consisting of a driving gear and a driven gear, the torque at the driven gear will increase as many times as the number of teeth of the driven gear is larger than that of the driving gear.
The figure obtained by dividing the number of driven gear teeth by that of the driving gear is called gear ratio. If a train consists of several pairs of gears, the overall ratio is the product of the gear ratios of all the gear pairs in the train.
To provide the different torques required under the varying operating conditions of a vehicle, the transmission incorporates several pairs of gears with different gear ratios.
If an intermediate gear is introduced between the driving gear and the driven gear, the rotation of the driven gear will be reversed.
The transmission consists of a housing, an input shaft and gear, an output and gear, an idler shaft, a reverse gear, a cluster of gears and a gear shift mechanism.
The cast iron housing has upper and side covers and bores for the installation of shafts. The bottom and side walls are provided with holes for filling and draining oil.
The input shaft is made of steel integral with the driving gear and the rim. The front end of the input shaft is installed on the bearing in the bore of the crankshaft, while the rear end rotates in the bore of the front wall of the housing. The input shaft is arranged so that only the driving gear and the rim are accommodated inside the housing while the splined potion of the shaft protruding from the transmission carries the hub of the clutch driven disk. The output shaft is splined and rests with its front end on a roller bearing installed in the bore of the input shaft. The other end of the output shaft rotates in a ball bearing in the transmission housing wall. The output shaft splines carry the sliding gears. The output shaft is coaxial with the input shaft.
The idler shaft carries a cluster of gears of different sizes. The cluster is mounted in the roller bearings on an axle or, together with the shaft, on bearings in the housing wall bores. The idler shaft constantly rotates with the input shaft because their gears are in constant mesh. The reverse gear(a single gear or a two-gear cluster) rotates on an axle secured in the holes of the housing walls.
The gear shift mechanism is designed for engaging gears, setting them neutral and engaging the reverse speed. The speeds are changed by shifting the gears or sleeves along the output shaft. The transmission type depends on the number of the sliding gears or sleeves. The transmission with two sliding gears or synchronizer sleeves is called two-range, with three gears, three-range. Depending on the number of forward speeds there are three-,four- and five-speed transmissions. The gear shift mechanism is mounted on the top cover. The shift lever is arranged on the cover or on the bracket of the lever support.
汽車的基本機械機構
汽車工業(yè)是一種迅速發(fā)展的工業(yè)。從十八世紀后期第一輛汽車出現(xiàn)在公路上后，這一工業(yè)便迅猛發(fā)展起來。如今全世界成千上萬的工廠生產著各種各樣的汽車。汽車行業(yè)也匯聚了千千萬萬的人。汽車發(fā)動機廣泛地應用于配有巨大動力的機械中，如農業(yè)、建筑業(yè)、制造業(yè)。不同類型的小型發(fā)動機也應用于植草機、動力鋸、除雪機等類似的設備中。汽車行業(yè)是一個發(fā)展著的、需求著的行業(yè)，似乎永遠找不到它的盡頭和飽和點。汽車、運輸工具、發(fā)動機有著巨大的需求量。這一行業(yè)同樣需要受過鍛煉的、有經驗的精英，來診斷這些機動車輛的故障、修理和更新機動車的零件、變速器、推動軸、差分器、車軸、操縱系統(tǒng)、剎車系統(tǒng)、暫停部件、空調裝置、發(fā)熱器、機身以及玻璃制造等。
汽車由五個基本的機械機構或部件組成。它們是：
（1）發(fā)動機，它是動力的源泉，包括燃料、潤滑劑、冷卻和電氣系統(tǒng)。
（2）框架，它支持發(fā)動機、車輪、操縱和剎車系統(tǒng)，以及機身。
（3）傳動系，它將來自發(fā)動機的動力（經過離合器、調速器、傳動軸、差分器和車軸）傳送到車輪。
（4）機身。
（5）機身附件，它包括加熱器、燈光、擋風玻璃擦等等。
發(fā)動機是使得汽車運行的動力源泉。它通常叫做一個內置的燃燒發(fā)動機，因為汽油是在發(fā)動機氣缸或燃燒腔內被燃燒的。這是相對于外置的發(fā)動機而言的（如蒸汽發(fā)動機），其燃燒發(fā)生在發(fā)動機的外部。發(fā)動機氣缸內的汽油的燃燒產生了動力。然后動力經過傳動系傳送到發(fā)動機再到車輪，這樣車輪轉動，汽車便開始運行。
在動力產生的過程中燃料系統(tǒng)起著重要的作用，因為它給發(fā)動機氣缸提供汽油。在每一個發(fā)動機氣缸里，蒸發(fā)出來的汽油和空氣組成的混合體進入氣缸，活塞推進氣缸，壓縮混合體，然后電火花點燃壓縮混合體，這樣活塞被迫向下。當然，在發(fā)動機內，活塞沒有完全推到氣缸外面，而是隨著混合體的燃燒，在氣缸內簡單地來回移動。在汽車車輪能夠轉動之前，活塞的線性運動必須轉變成旋轉運動。發(fā)動機機軸上的連桿和曲柄實現(xiàn)了這一轉變。
閥門將燃燒過的汽油蒸氣送出氣缸外面，同時把汽油蒸氣和空氣新鮮可燃混合氣送入氣缸。當他們被關閉或固定時（也就是推到端口上），端口被封閉，這樣氣體不能流通到端口。當他們被打開時，氣體可以流通到端口。
閥門是通過發(fā)動凸輪軸上的凸輪被打開的。凸輪有一個最高點，或圓形突出部分；每次當凸輪轉動時，突出部分在氣門挺桿之下，使得挺桿向上。挺桿將這個向上的運動傳動到推桿再傳送到搖桿臂。搖桿臂在它的支撐體上轉動并在閥桿上推下去，使得閥移到低處，也就是說閥被打開了。當凸輪轉動得足夠使突出部分移出挺桿之下時，承重的閥門彈簧將閥門退回到自己的位置。彈簧被彈簧座和鎖附在閥桿的下端。在發(fā)動機凸輪軸上每個閥門都有一個凸輪（每個氣缸兩個凸輪）。凸輪軸通過齒輪或鏈條齒和齒條受到機軸的驅動。
如果整個循環(huán)過程需要四次活塞運動，那么該發(fā)動機就叫做四沖程發(fā)動機，或四行程發(fā)動機。這四個行程是輸入、壓縮、發(fā)動、和排氣。
在輸入行程時，進氣閥是被打開的，活塞受到機軸旋轉的推動，移到下面?；钊倪@個移動引起了氣缸內的局部的真空，同時空氣通過進氣閥推進氣缸，以填補該真空。當空氣向氣缸移動時，它必須經過氣化器。那里充滿了汽油蒸氣。因此當活塞在輸入端移至下端時進入氣缸的是空氣和汽油蒸氣的混合體。
當活塞在進口端移到下止點時，進氣閥關閉?？刂浦M氣閥的凸輪的突出部分已經從閥門下面移走。因為另一個閥門也是關閉的，氣缸的上端被關閉?，F(xiàn)在，當轉動著的機軸將閥門推上時，已經進入氣缸的空氣和汽油蒸氣混合體被壓縮。直到活塞被推到上止點時，氣體被壓縮成原來的七分之一或八分之一。這就類似一加侖的空氣被壓所成一品托。究其原因是由于氣缸內部的高壓。
在壓縮行程，當活塞到達上止點時，氣缸火花塞產生一個電火花?；鸹ㄈ举|上是兩個粗鋼絲電極?；鸹ㄓ牲c火系統(tǒng)產生。它點燃了壓縮的空氣和汽油蒸氣混合體。由于高壓和高溫，發(fā)生了急劇的燃燒。此時，活塞頂端向下的壓力達到兩噸。這個巨大的推力使得活塞向下，同時巨大的沖力通過連桿和曲柄傳送到機軸。
在動力行程，由于汽油蒸氣的燃燒使得活塞受迫。當活塞達到下止點時，排氣閥被打開。這時，活塞又一次被返回，它推動氣缸內被燃燒過的氣體。到活塞到達上止點時，氣缸內被燃燒過的氣體被清除掉。排氣閥關閉，進氣閥開啟。活塞在下一個輸入行程時再次被返回。發(fā)動機運行時，這四個行程持續(xù)地重復著。
離合器是一種摩擦裝置，它用于從從動機構中聯(lián)合和拆分驅動力。在汽車的應用中，它用于與發(fā)動機調速輪相連，以提供發(fā)動機和手工傳送之間的平滑結合和正常脫離。
因此隨著發(fā)動機速度的降低，需要漸進裝載的應用，以獲得一個合理的和舒適的啟動。在裝配有手工傳動的汽車系統(tǒng)中，這可以通過一個機械離合器獲得成功。
離合器是通過摩擦獲得運行的。離合器的主要裝置是一個壓力盤和一個驅動板。壓力盤外加有調速輪，而驅動板和傳動輸入軸相品配。壓力盤通過彈力壓住驅動盤，這樣扭矩由于發(fā)動機和傳送的輸入軸之間的摩擦力而被傳動。
汽車一般裝有干式彈力離合器。之所以稱之為干的是因為壓力盤和驅動板是干的，相對于油式離合器，它是浸泡在油中運行的。之所以稱之為彈力的是由于壓力盤和驅動板是靠彈力相互壓在一起的，同時在某個時刻被釋放到汽車的齒輪或剎車裝置中。
除了壓力盤和驅動盤，離合器還包含有一個外殼、釋放桿、釋放軛、壓力彈簧和一個控制連接。離合器外殼是一個鋼鐵沖壓，由螺釘裝載調速器上。釋放桿通過支撐螺釘確保在外殼內部。釋放桿的外部端被放置在壓力盤中。這樣的裝置允許壓力盤接近或離開外殼，并一直隨著調速盤而轉動。沿壓盤和離合器蓋之間的圓周均勻分布的彈簧加住壓盤與飛輪之間的從動盤。
彈簧的安裝依賴于外殼和壓力盤提供的發(fā)射孔和插槽。為了防治彈簧過熱，壓力盤插槽配有熱的絕緣墊圈。
液壓制動離合器分離裝置由一個踏板、分離彈簧、主氣缸、氣力調壓器、管道、軟管、分離叉的桿組成。主氣缸供應一個附有杯子的活塞