曲軸銑端面打中心孔組合機床及專用夾具設計【銑端面】【說明書+CAD】

購買設計請充值后下載，資源目錄下的文件所見即所得，都可以點開預覽，資料完整，充值下載可得到資源目錄里的所有文件?！咀ⅰ浚篸wg后綴為CAD圖紙，doc,docx為WORD文檔，原稿無水印，可編輯。具體請見文件預覽，有不明白之處，可咨詢QQ:12401814 發(fā)任務書日期: 2010 年 2 月 22 日任務書填寫要求1畢業(yè)設計（論文）任務書由指導教師根據各課題的具體情況填寫，經學生所在專業(yè)的負責人審查、系領導簽字后生效。此任務書應在畢業(yè)設計（論文）開始前一周內填好并發(fā)給學生；2任務書內容必須用黑墨水筆工整書寫或按教務處統一設計的電子文檔標準格式（可從教務處網頁上下載）打印，不得隨便涂改或潦草書寫，禁止打印在其它紙上后剪貼；3任務書內填寫的內容，必須和學生畢業(yè)設計（論文）完成的情況相一致，若有變更，應當經過所在專業(yè)及系主管領導審批后方可重新填寫；4任務書內有關“系”、“專業(yè)”等名稱的填寫，應寫中文全稱，不能寫數字代碼。學生的“學號”要寫全號；5任務書內“主要參考文獻”的填寫，應按照國標GB 77142005文后參考文獻著錄規(guī)則的要求書寫，不能有隨意性；6有關年月日等日期的填寫，應當按照國標GB/T 74082005數據元和交換格式、信息交換、日期和時間表示法規(guī)定的要求，一律用阿拉伯數字書寫。如“2008年3月15日”或“2008-03-15”。畢 業(yè) 設 計（論 文）任 務 書1本畢業(yè)設計（論文）課題應達到的目的： 培養(yǎng)學生綜合運用所學基礎理論、專業(yè)知識和各項技能，設計專用組合機床，用于柴油機曲軸銑端面打中心孔的加工，提高分析與解決實際問題的能力，進行較為系統的工程訓練。重點提高調查研究、獨立工作、設計計算和邏輯思維、撰寫科技論文的能力，為實際工作奠定基礎，達到人才培養(yǎng)的目的和大綱規(guī)定的要求。 2本畢業(yè)設計（論文）課題任務的內容和要求（包括原始數據、技術要求、工作要求等）：（1）加工曲軸規(guī)格生產綱領：1.5萬件/年；見曲軸零件加工部位簡圖零件材料：鑄鋼。（2）任務要求（1） 編制曲軸加工過程卡。（2） 編制曲軸加工工序卡。（3） 繪制被加工零件毛坯圖。（4） 繪制被加工零件的加工工序圖。（5） 繪制被加工零件的加工示意圖。（6） 繪制組合機床聯系尺寸圖。（7） 繪制銑端面打中心孔專用夾具裝配圖。(8) 繪制夾具主要零件圖。（9） 編寫設計說明書。要求圖紙規(guī)范，計算正確，譯文符合中文習慣，說明書條理清楚，語句通順。畢 業(yè) 設 計（論 文）任 務 書3對本畢業(yè)設計（論文）課題成果的要求包括畢業(yè)設計論文、圖表、實物樣品等： 關于組合機床設計1. 方案合理，加工裝配工藝性好。2. 進行必要的計算和驗算。3. 圖面整潔，視圖齊全，布局合理，線條、文字及尺寸標注等均應符合有關標準規(guī)定。完成規(guī)定的作圖任務, 編寫設計說明書。4主要參考文獻： 1 裘愉弢. 組合機床M. 北京：機械工業(yè)出版社，19952 徐英南. 組合機床及其自動線的使用與調整M. 北京：勞動人事出版社，19873 金振華. 組合機床及其調整與使用M. 北京：機械工業(yè)出版社，19904 沈延山，楊培德.生產實習與組合機床設計M. 大連：大連理工大學出版社，19895 現代實用機床設計手冊編委會. 現代實用機床設計手冊M. 北京：機械工業(yè)出版社， 20066 黃開榜，張慶春，那海濤. 金屬切削機床M. 哈爾濱：哈爾濱工業(yè)大學出版社，20067 劉守勇. 機械制造工藝與機床夾具M. 北京：機械工業(yè)出版社，20008 李洪. 機械制造工藝金屬切削機床設計指導M. 沈陽：東北工學院出版社，19889 方子良. 機械制造技術基礎M. 上海：上海交通大學出版社，200410 胡小秋， 李琦， 等. 直徑同軸孔精鏜工序引刀裝置設計J.組合機床與自動化加工技術，2000（7）：4244畢 業(yè) 設 計（論 文）任 務 書5本畢業(yè)設計（論文）課題工作進度計劃：起 迄 日 期工 作 內 容 2009 年2月23日 3 月 4 日 3月 5 日 3 月15日3月16日 3 月31日4月 1 日 4 月10日4月15日 4 月30日5月 4 日 5 月18日5月19日 5 月25日理解課題性質、內容、指標及要求，安排進度，完成外文翻譯查閱文獻資料，完成開題報告工藝規(guī)程，總體設計 夾具設計編制設計說明書，完善圖卡完成論文及答辯前的全部準備工作，參加論文答辯所在專業(yè)審查意見：負責人： 年 月 日系意見：系領導： 年 月 日材 料 目 錄序號名 稱數量備 注1畢業(yè)設計(論文)選題、審題表12畢業(yè)設計(論文)任務書13畢業(yè)設計(論文)開題報告含文獻綜述14畢業(yè)設計(論文)外文資料翻譯含原文15畢業(yè)設計（論文）中期檢查表12009年 5 月注：畢業(yè)設計（論文）中期檢查工作結束后，請將該封面與目錄中各材料合訂成冊，并統一存放在學生“畢業(yè)設計（論文）資料袋”中（打印件一律用A4紙型）。 南 京 理 工 大 學畢業(yè)設計(論文)外文資料翻譯學院（系）： 南京理工大學紫金學院機械系 專 業(yè)： 機械工程及自動化 姓 名： 吳朋波 學 號： 060104232 (用外文寫) 外文出處： of Industrial and Manufacturing Systems Engineering 附 件： 1.外文資料翻譯譯文；2.外文原文。 指導教師評語： 簽名： 年 月 日 注：請將該封面與附件裝訂成冊。附件1：外文資料翻譯譯文第一部分 機械設計1.1 機械設計的簡介1.1.1 什么是機械設計機械設計是以滿足人類需要為目的，應用科學與技術裝配新的或改進的產品。這個工程技術的廣闊領域不僅關系到與該行為的本身就其大小，形狀和建筑細節(jié)，而且關系到在生產，銷售和使用該產品中所涉及的各種因素。一個產品可以被定義為任何生產項目，包括機械，結構，工具和儀器。執(zhí)行機械設計各種功能的人通常稱為設計師或者設計工程師?；旧蟻碚f，機械設計是一種創(chuàng)造性的活動。然而，除了創(chuàng)新，設計工程師也必須在工程技術基礎上有堅實的背景。1.1.2 機械設計的基本背景設計工程師必須要有在機械制圖，運動學，材料工程，材料拓展和制造工藝方面的工作知識。下面的將說明這些基本背景的每個議題與機械設計是如何關聯的：（1） 機械制圖。詳細的圖紙不僅必須注意到確切形狀，大小和每個組件材料的成分，裝配時也必須顯示總產品如何由每個部分以正確的順序緊固在一起。（2） 動力學。對有關這一問題的知識，例如，對以玩具“靈鳥”內部構造的分析，它包括初步的眼球轉動行為。一般情況下，在這種機器的設計初期階段，玩具和其內部構造的建立稱為動力學。（3） 機械學。用這一學說可以解析力量的問題，比如，一個人坐在椅子上，力也作用在放椅子的草地上。很顯然，他不小心從座位上跳起時可以破壞那個椅子。這種現象，實際上是適用于動態(tài)載荷，而不是草坪椅子設計時考慮到的承載。這種濫用的結果是過大的力量會造成永久性損傷。因此，在力學法律的使用中應考慮到合理的動態(tài)加載。（4） 工程材料。由于草坪躺椅一般來說是在戶外環(huán)境中使用，它所使用的油管是由鋁制造而成以有抗腐蝕的作用，所用的織帶是塑料材料制成，不會輕易惡化，即便長期暴露在陽光和水中。很顯然，材料的正確選擇是機械設計的重要方面。（5） 材料的強度。這是考慮到材料本身的組成部分是否強大到足以維持它通過力學的考驗。例如，草坪躺椅的鋁管狀部分的規(guī)格和形狀是以這樣一種方式確定的，這不會由于過度用力和變形而發(fā)生故障（在正常使用情況下）。應力和變形程度的大小取決于給定零件的規(guī)模和特定的形狀，以及其材料，結構和實際負荷力。（6） 生產過程?！办`鳥”不是一個簡單的玩具。每個組件是如何生產和整個玩具如何組裝使用的是生產技術中的方法。設計師正是由此來判斷成本的花銷。靈活的軸被應用在“靈鳥”上，因為他們簡化了昂貴的部件，并削減安裝和調整軸系僵化的勞動力成本。在處理結合的基礎過程使用中，有許多重要的考慮，這些必須在一般機械設計領域里詳細地闡述，其中包括安全，環(huán)境的影響，外觀和經濟。1.1.3 機械設計哲學一位不知姓名的作家寫過下面一首詩，名為設計師。它在說一個設計工程師以做出非常復雜的設計為樂，但產品的生產幾乎是不可能的。設計師他在電路板上設計彎道腦海里儲藏著美妙的設想他一邊搓著跳動的豆粒一邊說：“怎樣制造這個粗糙的機器呢？現在如果把這個部分造成直的我知道剛開始會有用但是那樣的話成型太簡單，也太枯燥了那樣永遠不會讓機器師覺得有挑戰(zhàn)所以我最好要弄個角在那兒然后看那些無知的機器師抓頭發(fā)那些用來包住螺絲帽的洞我會再往下放置以讓它們更加難敲打我敢打賭 現在這樣不會有效果它不能夠用腳踩或者用卡盤固定也不能用鉆子鉆或是放在地上事實上，這樣的設計是最好不過了。”他又看了看，叫起來：“最后成功是我的啦！這簡直是鬼斧神工?！焙茱@然，上述的詩是一個諷刺。但是，它明確強調了一名設計師在產品制造中的重要性。如前所述，機械設計的目的是滿足人類的需求。發(fā)明，發(fā)現和科學知識本身未必有益于人類，只有它們應用于產品的設計中去，利益才會產生。有時候，人類的需求也許被認可，但是如何實現它卻又很難決定。在這樣的原因可以被簡單地說成，在現階段，必須要花費的時間和努力并不能獲得對等的報酬。但是，如果該決定是為了以生產產品滿足人類需要，那么整個項目必須明確界定。機械設計應被視為是一個機會，這個機會就是如何利用創(chuàng)新人才進行產品設計，對系統進行分析，然后做出如何將產品合理制造的判斷。重要的是要理解工程的基本事實，而不是背誦純粹的事實和公式。任何事實或方程組，只有用于提供所有正確的決定和設計良好的產品才能存在。另一方面，任何計算必須做的極其謹慎和精準。例如，如果一個小數點是錯誤的，否則一個合理的設計可能無法正常使用。良好的設計需要嘗試新的想法并愿意冒一定的風險，因為他們知道，如果新的想法不起作用的話，那么只能用現存的方法。因此，作為一個設計師必須要有耐心，因為時間和精力的花費沒有成功的保證。創(chuàng)建一個全新的設計，一般都需要拋棄很多老的方法。這并不容易，因為很多人都依賴熟悉的思想，技術和態(tài)度。設計工程師應不斷尋找方法，以改善現有的產品，必須決定什么是陳舊的，應該用新的成熟的概念，納入未經試驗的想法。新的設計一般有“錯誤”，或不可預見的問題，這些問題必須在制定新的設計的優(yōu)良特性前解決。因此，只有在更高的風險下存在有優(yōu)越的行為機會。應該強調的是，如果設計不保證采納新的方法，這種方法只為了改變起見是不能被采納的。在設計的初期階段，在無任何制約因素的條件下，應允許創(chuàng)造性的蓬勃發(fā)展。雖然許多不切實際的想法可能在設計的早期階段出現，但通常很容易消除在制定具體細節(jié)之前。這樣一來，創(chuàng)意不會被抑制。很多時候，設計開發(fā)一個以上的產品時，取決于和其他產品在哪里可以相互比較。最終將現有的思想應用在被拒絕的設計上，并沒有顯示為一個整體預想的樣子，這是完全有可能的。心理學家經常談論讓人們努力適應他們的機器運作。很重要的是，設計工程師的責任在于努力讓機器去適應人。這不是一項容易的任務，因為一般人實在不能操作某些層面和最優(yōu)的程序。然而，必須考慮到許多操作者的功能，包括以下幾方面：(1) 尺寸和手輪，旋鈕，開關和腳踏板的位置; (2) 工作區(qū)的空間分配；(3) 通風狀況；(4) 顏色和光線；(5) 操作的力度；(6) 安全裝置；(7) 單調操作議案；(8) 操作驗收。1.1.4 設計的交流另一個重要的需要被承認的一點就是一個設計工程師必須能夠與其他人交流意見，如果這些意見被采納的話。一開始，設計人員必須傳達一個初步設計從而得到管理層的批準。這通常是由與繪畫的布局和口頭書面材料一并討論。為了有效地溝通，以下幾個問題必須要回答：（1） 設計是否真正滿足人的需要？（2） 與對手公司現有產品相比，是否更加具有競爭力？（3） 生產是否節(jié)儉？（4） 能不能夠簡單易行？（5） 是否能賣出獲得利潤？只有時間才能提供對上述問題的真正答案，但有關產品的設計，制造和推向市場，只有初步肯定回答。設計師也必須通過使用細節(jié)和裝配圖結合最終的設計制造。很多時候，在制造循環(huán)過程中會發(fā)生問題。這可能是在對產品部件進行尺寸標注或放寬時以便它可以更容易地生產時所需要的一個變化。這是屬于技術變化類別，設計師必須接受這種變化以使該產品的功能不會受到不利影響。在其他情況下，在組裝或測試過程中可能會出現設計不足，恰好在出貨之前。這始終是更好的方法，要做到這一點，設計者應不斷努力，爭取找到更好的方法。11.5活塞發(fā)動機和汪克爾引擎毫無疑問，汽車是20世紀對人們具有最深遠影響的因素之一。在20世紀的頭70年采用傳統的往復式活塞發(fā)動機，汽車一直是世界最大的工業(yè)基礎。在美國大多數人都能夠獲得屬于自己的汽車駕駛執(zhí)照。然而，這導致了大氣污染的新問題，簡單說來就是指大氣層逐漸積累越來越多對人生命有害的化學污染物。不斷增加地空氣污染導致的結果之一就是不再相信其他類型的發(fā)動機，那些承諾在廢氣排放過程中產生較少的污染。其中一個類似引擎最近得到了很大發(fā)展的是汪克爾發(fā)動機。它很可能取代活塞發(fā)動機。另外，同時出現的問題是現有原油相比所需的汽油短缺。因此，一種更有效的以及產生的污染物少得多的引擎也是必要的。令人驚訝的是，第一個四沖程活塞式發(fā)動機是1866年8月由尼可拉斯奧托和德國的尤格朗根制造的。現今的活塞式發(fā)動機工程基本上是和奧托和蘭根建立的發(fā)動機一樣的原則。事實上，在現代活塞熱能操作過程稱為奧托循環(huán)。另一方面，1954年才出現汪克爾轉子發(fā)動機，那是也是德國人的費克爾發(fā)現他能完全地用一個旋轉式發(fā)動機實現奧托循環(huán)。從效率的角度來看，汪克爾發(fā)動機優(yōu)越，因為它比較簡單，包含較少的零件和操作更安靜。但是直到20世紀60年代才有人提出為汪克爾發(fā)動機的發(fā)展做出大量努力。這種現象產生最主要的原因是活塞式發(fā)動機在當時已經是一個成熟可靠的工業(yè)分支。在60年代初，人類需要一種廢氣排放中污染少得多的引擎，這顯然率先引起了新引擎的發(fā)展。1967年，日本東洋工業(yè)制造業(yè)采用汪克爾發(fā)動機生產馬自達汽車和美國開始見證了70年代初以來發(fā)動機發(fā)展所帶來的影響。認識到汪克爾發(fā)動機的巨大潛力，通用汽車公司在1971年與汪克爾的專利持有人（汪克爾專線H和奧迪NSU在和美國許可證，柯蒂斯賴特）簽署了五千萬美元的協議。從1971年到1975年，通用汽車公司支付5000萬美元，把汪克爾發(fā)動機發(fā)展為本公司的傳導。1975年以后，通用汽車可以使用自己設計的無需支付任何額外的許可費。接下來，讓我們驗證一下活塞式發(fā)動機和汪克爾發(fā)動機的設計和操作。附件2：外文原文PART 1 MACHINE DESIGN1.1 INTRODUCTION TO MACHINE DESIGN1.1.1 What Is Machine Design Machine design is the application of science and technology to device new or improved products for the purpose of satisfying human needs. It is a vast field of engineering technology which not only concerns itself with the original conception of the conduct in terms of its size, shape and construction details, but also considers the various factors involved in the manufacture, marketing and use of the product.A product can be defined as any manufactured item, including machines, structures, tools, and instruments. People who perform the various functions of machine design are typically called designer, or design engineer. Machine design is a creative activity Basically. However, in addition to being innovative, a design engineer must also have a solid background in the fundamentals of engineering technology.1.1.2 Fundamental Background for Machine DesignA design engineer must have working knowledge in the areas of mechanical drawing, kinematics, material engineering, strength of materials and manufacturing processes. The following statements will indicate how each of these basic background subjects relates to machine design:(1) Mechanical drawing. Detailed drawings must be prepared noting the exact shape, size and material composition for each component, assembly drawings showing how the total product is put together by fastening each part in proper sequence are also needed.(2) Kinematics. Knowledge of this subject, for example, would permit analysis of the motion of the internal mechanism of Smarty Bird This analysis would include the attainment of the desired eye-rolling action. Normally, the very creation of the toy and its internal mechanism would occur during this initial phase of machine design called kinematics.(3) Mechanics. Use of this subject provides an analysis of the forces which, for example,act upon a lawn chair when a person is seated in it. Obviously, a person can damage the lawn chair by carelessly jumping on the seat. This motion, in effect, applies dynamic loading instead of the gradually applied loading taken into consideration when the lawn chair was designed. The result of this misuse is excessively large forces that can cause permanent damage. Therefore, using the laws of mechanics, a reasonable amount of dynamic loading should be taken intoPart 1 Machine Design2account during the early design phase.(4) Materials of engineering. Because the lawn chair is commonly used in an outdoorenvironment, the tubing is made of aluminum to resist corrosion. The webbing is made of a plastic material that will not readily deteriorate with sustained exposure to sunlight and moisture. Obviously, the proper selection of materials is a vital area of machine design.(5) Strength of materials. The subject concerns itself with whether or not a part is strongenough to sustain the forces it will experience evaluated from mechanics. For example, the size and shape of the aluminum tubular sections of the lawn chair are determined in such a way, that failure will not occur (under normal use) due to excessive stresses and deflections. The magnitude of stresses and deflections depends on the size and shape of a given part as well as on its material, composition, and actual loads.(6) Manufacturing processes. Smarty Bird is no simple toy. How each component isproduced and how the entire toy is assembled are established by using methods learned in manufacturing technology. It is here that a designer comes to grips with the reality of costs. The flexible shafts are used in Smarty Bird because they simplify of manufacturing by eliminating expensive parts and by cutting the labor costs of installing and aligning rigid shafting. In conjunction with the use of the processing fundamentals, there are many significant considerations, which must be detail with in the general field of machine design. Among these are safety, environmental effects, appearance, and economy.1.1.3 Philosophy of Machine DesignAn unknown author wrote the following poem called “The designer.” It relates that a designengineer may enjoy making a design so complex that manufacturing of the product is virtuallyimpossible.THE DESIGNERThe designer bent across his boardWonderful things in his head wore stored.Said he as he rubbed his throbbing bean,“How can I make this tough machine?Now if I make this part just straightI know that it will work first rate,But thats too easy to shape and boreIt never would make the machinist sore.So I better put an angle thereThen watch those babies tear their hair.And there are the holes that hold the capIll put them down where theyre hard to tap.Now this wont work, Ill bet a buck,Technical English Through Reading3It cant be held in a shoe or chuck,In cant be drilled and it cant be ground,In fact, the design is exceedingly sound.”He looked again and cried: “At last!Success is mineit cant even be cast.”O(jiān)bviously, the foregoing poem is a satire. However, it clearly emphasizes the importanceof a design engineer in establishing the manufacturability of a product.As stated previously, the purpose of machine design is to produce a product that willservea need for man. Inventions, discoveries and scientific knowledge by themselves do notnecessarily benefit people; only if they are incorporated into a designed product will a benefit be derived. It should be recognized, therefore, that a human need must be identified before aparticular product is designed.Sometimes a human need may be recognized, but a decision is reached to do nothing about it. The reason could simply be that, at the moment, the rewards do not justify the time and effort that must be expended. If, however, the decision is reached to satisfy the human need bymanufactured product, the entire project must be clearly defined.Machine design should be considered to be an opportunity to use innovative talents toenvision a design of a product, to analyze the system and then make sound judgments on how the product is to be manufactured. It is important to understand the fundamentals of engineering rather than memorize mere facts and equations. There are no facts or equations, which alone can be used to provide all the correct decisions, required producing a good design. On the other hand, any calculations made must be done with the utmost care and precision. For example, if a decimal point is misplaced, an otherwise acceptable design may not function.Good designs require trying new ideas and being willing to take a certain amount of risk,knowing that if the new idea does not work the existing method can be reinstated. Thus adesigner must have patience, since there is no assurance of success for the time and effortexpended. Creating a completely new design generally requires that many old and will-established methods be thrust aside. This is not easy since many people cling to familiar ideas, techniques, and attitudes. A design engineer should constantly search for ways to improve an existing product and must decide what old, proven concepts should be used and what new, untried ideas should be incorporated.New designs generally have “bugs” or unforeseen problems which must be worked outbefore the superior characteristics of the new designs, can be enjoyed. Thus, there is a chance for a superior conduct, but only at higher risk. It should be emphasized that, if a design does not warrant radical new methods, such methods should not be applied merely for the sake of change.During the beginning stages of design, creativity should be allowed to flourish without agreat number of constraints. Although many impractical ideas may arise, it is usually easy to eliminate them in the early stages of design before manufacturing requires firm details. In thisPart 1 Machine Design4 way, innovative ideas are not inhibited. Quite often, more than one design is developed, up to the point where they can be compared against each other. It is entirely possible that the design that is ultimately accepted, will use ideas existing in one of the rejected designs that did not show as overall promise.Psychologists frequently talk about trying to fit people to the machines they operate. It isessentially the responsibility of the design engineer to strive to fit machines to people. This is not an easy task, since there is really no average person for which certain operating dimensions and procedures are optimums. However, many human operator features must be consideredincluding the following:(1) Size and locations of hand wheels, knobs, switches, and foot pedals;(2) Space allocations for working areas;(3) Ventilation;(4) Colors and lighting;(5) Strength of operator;(6) Safety features;(7) Monotonous operator motions;(8) Operator acceptance.1.1.4 Communication of DesignAnother important point which should be recognized, is that a design engineerMust be able to communicate ideas to other people if they are to be incorporated. Initially, the designer must communicate a preliminary design to get management approval. This is usually done by verbal discussions in conjunction with drawing layouts and written material. To communicate effectively, the following questions must be answered:(1) Does the design really serve a human need?(2) Will it be competitive with existing products of rival companies?(3) Is it economical to produce?(4) Can it be readily maintained?(5) Will it sell and make a profit?Only time will provide the true answers to the preceding questions, but the Product should be designed, manufactured, and marketed only with initial affirmative answers. The design engineer also must communicate the finalized design to manufacturing through the use if detail and assembly drawings.Quite often, a problem will occur during the manufacturing cycle. It may be that a changeis required in the dimensioning or tolerance of a part so that it can be more readily produced.This falls in the category of engineering changes that must be approved by the design engineer so that the product function will not be adversely affected. In other cases, a deficiency in the design may appear during assembly or testing just prior to shipping. These are always a better way that to do it and the designer should constantly strive towards finding that better way. One Technical English Through Reading 5reality that needs to be kept in mind is that many of the products that will be in existence ten years from now have probably not yet even been conceived.1.1.5 Piston Engine Versus the Wankel EngineThe automobile, without a doubt, has had one of the most profound influences on people in the twentieth century. Powered predominantly by the conventional reciprocating piston engine during the first seven decades of the twentieth century, the automobile has been the basis for the largest industry in the world. Most people in the United States who are old enough to obtain a license own automobiles. This, however, has contributed to the new problem of air pollution, which, stated simply, means that the atmosphere is gradually accumulating more and more chemical contaminants harmful to human life. One of the results of increasing air pollution has been a hard look at other types of engines which promise to provide fewer pollutants in exhaust emissions. One such engine recently receiving a great deal of development is the Wankel engine. It is a very possible replacement for the piston engine. A second, concurrent problem is a shortage of available crude oil from which gasoline is derived. Thus, there is also a need for a much more efficient engine as well as one which produces far fewer pollutants. Surprisingly enough, the first four stroke piston engine was built in 1866 by Nickolaas August Otto and Euger Langen of Germany. The present-day piston engine works on basically the same principles as the one built by Otto and Langen. In fact, the thermodynamic processoperating in the modern piston is called the Otto cycle. On the other hand, the Wankel rotary engine was not invented until 1954, when Felix Wankel, also of Germany, discovered that he could reproduce the Otto cycle with a purely rotary-type engine. From an efficient point of view, the Wankel engine is superior because it is simpler, contains fewer parts and operates more quietly. It wasnt, however, until the 1960s that much effort was put into the development of the Wankel engine. The main reason for this wasthat the piston engine was already a proven, reliably working power plant. It was the human needs for an engine with far less polluting exhaust emissions, whichapparently spearheaded new engine developments in the early 1960s. In 1967, Toyo Kogyo of Japan was manufacturing Wankel-powered Mazda automobiles and the United States began to witness the impact by the early 1970s.Recognizing the great potential of the Wankel engine, General Motors in 1971 signed a $50 million licensing agreement with Wankel patent holders (Wankel Gmb H and Audi NSU and the U. S. licensee, Curtiss Wright). From 1971 to 1975, General Motors is to pay the $50 million and develop the Wankel engine for is own conduction. After 1975, General Motors can use its own designed Wankel engines without paying any additional licensing fees. Next, let us examine the design and operation of the piston and Wankel engines.1.1.6 The Four-stroke Automotive Piston EnginePart 1 Machine Design6Figure 1-1 shows the conventional four-stroke piston engine, which contains a pistonreciprocating in a fixed cylinder inside an engine block. A connecting rod is attached to the piston by a wrist pin and to the crank by a crankpin. As the piston reciprocates, the crank, and hence the crankshaft, is forced to rotate inside of bearings. The detailed operation is as follows:(a) Intake stroke (Figure 1-1a). The intake valve opens, allowing a mixture of fuel and airto enter the cylinder. The exhaust valve is closed during most of the stroke. The crankshaft rotates 180 degrees while the piston moves from top dead center (TDC) to bottom dead center (BDC).(b) Compression stroke (Figure 1-1b). Both valves are closed during this stroke. Thefuel-air mixture is compressed as the piston rises. Near the end of the stroke, the spark plug fires. The piston moves from BDC to TDC as crankshaft rotates 180 degrees.(c) Power stroke (Figure 1-1c). Both valves are initially closed. The fuel-air mixture burns and increases the temperature. This causes the gas to expand and drive the piston down withpower. The exhaust valve opens near the end of the stroke. The power stroke occurs while the crankshaft rotates through 180 degrees.(d) Exhaust stroke (Figure 1-1d). The exhaust valve opens fully as the products of combustion are removed from the cylinder. The intake valve opens near the end of the exhauststroke. During this stroke, the crankshaft rotates 180 degrees.The following observations should be noted for the four-stroke piston engine:(1) There are four different strokes for one complete cycle of operation.(2) One complete cycle of operation (and thus each power stroke) requires two revolutionof the crankshaft.(3) Timing is important. A camshaft is driven by the crankshaft through a gear system ortiming chain. One rotation of the camshaft has a separate cam for each intake valve and aseparate cam for each exhaust valve. For example, a six-cylinder engine will have twelve cams.(4) Th