無軸攪拌機(jī)傳動(dòng)系統(tǒng)的設(shè)計(jì)【含圖紙】
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編號(hào)無錫太湖學(xué)院畢業(yè)設(shè)計(jì)(論文)相關(guān)資料題目: 無軸攪拌機(jī)傳動(dòng)系統(tǒng)的設(shè)計(jì) 信機(jī) 系 機(jī)械工程及自動(dòng)化專業(yè)學(xué) 號(hào): 0923829 學(xué)生姓名: 龍 躍 指導(dǎo)教師: 韓邦華 (職稱:副教授 ) (職稱: )2013年5月25日目 錄一、畢業(yè)設(shè)計(jì)(論文)開題報(bào)告二、畢業(yè)設(shè)計(jì)(論文)外文資料翻譯及原文三、學(xué)生“畢業(yè)論文(論文)計(jì)劃、進(jìn)度、檢查及落實(shí)表”四、實(shí)習(xí)鑒定表無軸攪拌機(jī)傳動(dòng)系統(tǒng)的設(shè)計(jì)1 緒論1.1 無軸式攪拌機(jī)研究發(fā)展現(xiàn)狀改革開放35年以來,中國混凝土攪拌機(jī)市場從無到有、從小到大。目前,我國年產(chǎn)水泥混凝土約為15億,攪拌機(jī)的年產(chǎn)量也居世界前列。相比較而言,我國具有的自主知識(shí)產(chǎn)權(quán)技術(shù)也很少。但隨著商品混凝土的大力推廣、工程建設(shè)施工的高效率化、高質(zhì)量化和高效益化,推動(dòng)了混凝土攪拌設(shè)備向高效率、高質(zhì)量的方向不斷發(fā)展,一些傳統(tǒng)設(shè)備己經(jīng)無法滿足施工要求。在現(xiàn)有的攪拌機(jī)的基礎(chǔ)上,對(duì)新型攪拌設(shè)備的研究和開發(fā),提高混凝土攪拌機(jī)的設(shè)計(jì)水平,同時(shí)帶動(dòng)相關(guān)技術(shù)的發(fā)展,創(chuàng)造一個(gè)良好的生產(chǎn)空間;對(duì)高效混凝土攪拌機(jī)的開發(fā),推動(dòng)攪拌及機(jī)事業(yè)性能的快速發(fā)展,生產(chǎn)出適應(yīng)市場要求、具有高可靠性和較強(qiáng)競爭力的攪拌機(jī)。依據(jù)新的攪拌原理,采用理論探討和試驗(yàn)分析相結(jié)合的辦法,能方便解決大型雙臥軸攪拌機(jī)存在的低效率問題,如果生產(chǎn)工業(yè)化成功應(yīng)用,一定為研制具有自主知識(shí)產(chǎn)權(quán)的高效攪拌機(jī)做出重大貢獻(xiàn)。長期以來,國內(nèi)外攪拌設(shè)備雖然種類很多,但他們的共同特點(diǎn):有一根軸貫穿整個(gè)攪拌空間?!半p螺旋軸攪拌機(jī)”是一種新型的“無軸”攪拌機(jī),它具有雙倍的徑向進(jìn)給料流,雙倍的軸向進(jìn)給料流,雙倍的剪切力,使攪拌效率達(dá)到普通攪拌機(jī)的兩倍,能耗更小。“雙螺旋軸攪拌機(jī)”無水平的主軸,不會(huì)產(chǎn)生混凝土黏合中心軸并產(chǎn)生結(jié)塊形成抱軸的現(xiàn)象,更適合于加工粘性強(qiáng)和添加有纖維的混凝土材料。20世紀(jì)70年代未至80年代初,我國為了適應(yīng)建筑業(yè)有關(guān)方面混凝土發(fā)展的需要,在引進(jìn)國外攪拌機(jī)的基礎(chǔ)上,研制出了10多種混凝土攪拌樓(站)。經(jīng)過引進(jìn)研究、自主開發(fā)生產(chǎn)等幾個(gè)階段,到本世紀(jì)初,我國攪拌機(jī)技術(shù)得到更大的發(fā)展,在產(chǎn)品型號(hào)和生產(chǎn)數(shù)量上,都達(dá)到了一定規(guī)模,出現(xiàn)了一批更具有自主知識(shí)產(chǎn)權(quán)的新產(chǎn)品,并開始形成了一個(gè)具有一定規(guī)模和競爭能力的產(chǎn)業(yè)。2006年,我國生產(chǎn)裝機(jī)容量0.56的攪拌站2100多臺(tái),已成為攪拌設(shè)備的研究和生產(chǎn)大國。自上世紀(jì)八十年代初已經(jīng)開始研制JS系列雙臥軸混凝土攪拌機(jī),一直到現(xiàn)在,已研制出從JS35JS6000系列攪拌機(jī),一直處于國際領(lǐng)先水平,尤其從2000年開始采用UG等三維軟件,對(duì)攪拌機(jī)研究進(jìn)行優(yōu)化設(shè)計(jì),對(duì)攪拌設(shè)備進(jìn)行了動(dòng)力分析和受力分析,大大提高產(chǎn)品的可靠性,達(dá)到國際先進(jìn)水平。這些攪拌機(jī)的研制,基本滿足了我國混凝土發(fā)展的需求,但隨著主機(jī)市場的不斷發(fā)展,新型主機(jī)的需求越來越多。無軸式攪拌機(jī)在國外也處在研究發(fā)展階段。1.2攪拌機(jī)的各種類型及特點(diǎn)目前使用的攪拌機(jī)就其原理而言,其基本上可分為自落式和強(qiáng)制式兩大類。自落式攪拌機(jī)有較長的歷史,早在20世紀(jì)初,混凝土攪拌設(shè)備開始不斷出現(xiàn)。50年代后,人們研發(fā)出反轉(zhuǎn)出料式和傾翻出料式的雙錐形攪拌機(jī),同時(shí),其他一些攪拌機(jī),如裂筒式攪拌機(jī)等相繼問世。運(yùn)作時(shí),拌筒繞著水平軸線旋轉(zhuǎn),加入攪拌筒內(nèi)的物料,葉片將物料提升至一定高度,然后借助自重下落,這樣不斷的循環(huán)運(yùn)動(dòng),達(dá)到攪拌的理想效果。自落式混凝土攪拌機(jī)的結(jié)構(gòu)簡單,一般以攪拌塑性混凝土為主。但自落式攪拌機(jī)已不符合國家的有關(guān)標(biāo)準(zhǔn),屬于淘汰產(chǎn)品,所以本文不作研究。強(qiáng)制式攪拌機(jī)從20世紀(jì)50年代初興起后,得到了迅速的發(fā)展和生產(chǎn)推廣。最先出現(xiàn)的是圓盤立軸式強(qiáng)制混凝土攪拌機(jī)。這種攪拌機(jī)分為渦槳式和行星式兩種。19世紀(jì)70年代后,隨著輕骨料的出現(xiàn),研制出了圓槽臥軸式強(qiáng)制攪拌機(jī)。 實(shí)踐證明,在上述混凝土攪拌設(shè)備的攪拌主機(jī)在工作中經(jīng)常出現(xiàn)混凝土 “抱軸”現(xiàn)象。如果不及時(shí)停機(jī)清除,“抱軸”的混凝土?xí)絹碓蕉啵瑢?huì)引發(fā)攪拌機(jī)電機(jī)因過載而堵轉(zhuǎn),造成電機(jī)燒毀。1.3無軸式攪拌機(jī)特點(diǎn)無軸式攪拌機(jī)與以上所述的各種臥軸式攪拌機(jī)相比有以下一些優(yōu)點(diǎn):(1)解決了攪拌機(jī)運(yùn)作中普遍存在的抱軸現(xiàn)象;(2)減小了因攪拌臂的重量產(chǎn)生的大量彎矩;(3)解決了因攪拌臂的安裝而產(chǎn)生的偏心力,緩解了對(duì)軸端的沖擊;(4)攪拌機(jī)上安裝攪的拌臂和連接套數(shù)量大,占用攪拌筒的空間大,減少了筒內(nèi)的有效容積,無軸攪拌機(jī)攪拌裝置結(jié)構(gòu)簡單,構(gòu)思靈活,有效提高了攪拌筒的攪拌容積;(5)無軸式攪拌機(jī)不需攪拌臂的更換,維修也方便,大大降低了工人的工作量;(6)減少了由于抱軸引起的沖洗次數(shù),節(jié)約用水量,同時(shí)也減少了對(duì)環(huán)境的污染,成本得到降低;1.4 攪拌機(jī)的分析及設(shè)計(jì)任務(wù) 1.4.1 攪拌機(jī)常見問題的原因分析 實(shí)際工作中,攪拌機(jī)的攪拌主體在工作中經(jīng)常出現(xiàn)混凝土“抱軸”現(xiàn)象。如果不及時(shí)停機(jī)清除,“抱軸”的混凝土?xí)絹碓蕉?,將?huì)引起電機(jī)過載而發(fā)生堵轉(zhuǎn),造成電機(jī)燒毀或產(chǎn)生破壞。經(jīng)過調(diào)查和研究,普遍贊同攪拌機(jī) “抱軸”產(chǎn)生的原因是可以避免的,原因可以分為兩大類:設(shè)計(jì)不當(dāng)和使用不規(guī)范。表現(xiàn)形式如下:(1) 投料設(shè)備設(shè)計(jì)的不合理。比如物料和進(jìn)水口位置及方向設(shè)計(jì)不合理,導(dǎo)致軸上堆積大量物料,粘結(jié)在軸上的物料卡住轉(zhuǎn)軸;(2)進(jìn)水口方向和沖洗方向不得當(dāng),另外沖水壓力過低也是原因之一。沖洗攪拌筒時(shí),攪拌器上粘著的大量物料清理不掉;(3) 攪拌筒的容積存在不合理利用率,容積利用率太小,攪拌時(shí),攪拌軸在混凝土上面,粘附在上面的物料得不到攪拌,從而慢慢凝固,阻礙軸的轉(zhuǎn)動(dòng); (4)操作人員在設(shè)備攪拌卸料后,沒有及時(shí)清理攪拌罐,同時(shí)攪拌軸上殘留的混凝土發(fā)生凝固,攪拌軸的表面上殘留粗糙不平的物料,干燥后凝固在軸上,以后就會(huì)越聚越多影響攪拌軸轉(zhuǎn)動(dòng)。 1.4.2 無軸攪拌的理念圖1.1“無軸”攪拌機(jī)葉片形式長期以來,國內(nèi)外攪拌機(jī)雖難種類繁多,但他們的共同特點(diǎn)就是有一跟軸貫穿整個(gè)攪拌空間。 “雙螺旋軸攪拌機(jī)”是一種新型的“無軸”攪拌機(jī),其葉片形狀如圖1.1所示。它具有雙倍的徑向物料流,雙倍的軸向物料流,雙倍的剪切力,使攪拌效率是普通攪拌機(jī)兩倍多,能耗更小。“雙螺旋軸攪拌機(jī)”無水平的主軸,不會(huì)產(chǎn)生混凝土骨料黏合中心軸上結(jié)塊形成抱軸現(xiàn)象,利于加工粘性較強(qiáng)和添加有纖維的特種混凝土材料。無攪拌臂的阻礙,使其空間更大。但是僅對(duì)其攪拌部分進(jìn)行的改進(jìn)還是不能達(dá)到真正的提高效率、節(jié)約能源的效果,所以這次我們?cè)趯?duì)一些公司、工廠進(jìn)行調(diào)研后,對(duì)其傳動(dòng)部件進(jìn)行深入研究確定了最初方案,對(duì)機(jī)器進(jìn)行改良,并達(dá)到理想效果。1.4.3 基本設(shè)計(jì)任務(wù)畢業(yè)設(shè)計(jì)的主要任務(wù)主要有:1、擬定傳動(dòng)方案;2、對(duì)減速器進(jìn)行設(shè)計(jì)計(jì)算;3、繪制攪拌機(jī)裝配部件裝配總圖一份和組要零件圖六份;4、按指定格式和要求撰寫畢業(yè)設(shè)計(jì)計(jì)算說明書。 1.4.4 畢業(yè)設(shè)計(jì)的目的畢業(yè)設(shè)計(jì)是對(duì)學(xué)生進(jìn)行工程師基本訓(xùn)練的重要環(huán)節(jié),通過畢業(yè)設(shè)計(jì)能達(dá)到以下目的: (1)鞏固、熟悉并綜合運(yùn)用所學(xué)的知識(shí);(2)培養(yǎng)理論聯(lián)系實(shí)際的學(xué)風(fēng);(3)熟悉進(jìn)行機(jī)械設(shè)計(jì)的一般步驟和常見問題,掌握機(jī)械設(shè)計(jì)的一般技巧;(4)學(xué)會(huì)查閱運(yùn)用技術(shù)資料;初步掌握對(duì)專業(yè)范圍內(nèi)的生產(chǎn)技術(shù)問題進(jìn)行研究的能力。1.5 課題研究背景及意義 1.5.1 課題研究背景隨著市場經(jīng)濟(jì)的不斷發(fā)展,同時(shí)國家加快城市建設(shè)、場所設(shè)施建設(shè)、高鐵事業(yè)等全面展開,并伴隨著一大批國家建設(shè)項(xiàng)目的啟動(dòng),國內(nèi)對(duì)無軸攪拌機(jī)的需求量越來越多。這為無軸攪拌行業(yè)提高了發(fā)展的進(jìn)程。商品混凝土的大力推廣和工程建設(shè)施工的高效益化、高質(zhì)量化、高效率化,從實(shí)際上推動(dòng)了無軸攪質(zhì)量,此外,攪拌設(shè)備的使用性能和研發(fā)方面得到迅速提高和發(fā)展。同時(shí),從市場需求看,隨著高速公路建設(shè)的普及和高速鐵路建設(shè)的啟動(dòng),施工質(zhì)量被用戶要求的越來越高,一些傳統(tǒng)攪拌設(shè)備已無法滿足越來越高的施工要求。 1.5.2 課題研究意義本課題通過理論分析,針對(duì)無軸攪拌機(jī)主要參數(shù)進(jìn)行理論分析;確定攪拌機(jī)主要參數(shù),完成課題研究內(nèi)容,為無軸攪拌機(jī)的設(shè)計(jì)提供參考。重點(diǎn)需要解決的問題是攪拌機(jī)中螺旋葉片的設(shè)計(jì)。利用SOLIDWORK完成各部分設(shè)計(jì),并在此基礎(chǔ)上完成二維工程圖的設(shè)計(jì)。要求圖樣繪制及標(biāo)識(shí)符合國家標(biāo)準(zhǔn)。圖面布局和比例合理、圖線清晰、表達(dá)正確。通過這次畢業(yè)設(shè)計(jì),希望對(duì)自己未來的事業(yè)和工作有所幫助,并提高自己各方面的能力,為以后的發(fā)展打下堅(jiān)實(shí)的基礎(chǔ)。由于本人水平有限,經(jīng)驗(yàn)不足,設(shè)計(jì)過程當(dāng)中存在許多不足之處,希望各位老師給予指教,一定虛心改正以期有更大的提高,在此致謝!2 傳動(dòng)方案及電動(dòng)機(jī)的選擇2.1 傳動(dòng)方案的選擇機(jī)器通常是由原電機(jī),傳動(dòng)系統(tǒng)和工作機(jī)三部分所組成。傳動(dòng)系統(tǒng)是將原動(dòng)機(jī)的運(yùn)動(dòng)和 動(dòng)力進(jìn)行傳遞與分配的作用,可見,傳動(dòng)系統(tǒng)是機(jī)器的重要組成部分。傳動(dòng)系統(tǒng)的質(zhì)量與成本在整臺(tái)機(jī)器中占有很大比重。因此,在機(jī)器中傳動(dòng)系統(tǒng)設(shè)計(jì)的好壞,對(duì)整部機(jī)器的性能、成本以及整體尺寸的影響都是很大的。所以合理地設(shè)計(jì)傳動(dòng)系統(tǒng)是機(jī)械設(shè)計(jì)工作地一重要組成部分。圖2.1 傳動(dòng)方案圖方案(b)方案(c)方案(a)合理的傳動(dòng)方案首先應(yīng)滿足工作機(jī)的性能要求,其次是滿足工作可靠、結(jié)構(gòu)簡單、尺寸緊湊、傳動(dòng)效率高、使用維護(hù)方便、工藝性和經(jīng)濟(jì)性好等要求。很顯然,要同時(shí)滿足這些要求肯定比較困難的,因此,要通過分析和比較多種傳動(dòng)方案,選擇其中最能滿足眾多要求的合理傳動(dòng)方案,作為最終確定的傳動(dòng)方案。為此,我們?cè)O(shè)計(jì)了如下三種傳動(dòng)方案,分別如圖2.1所示。下面進(jìn)行分析和比較:在圖2.1方案(a)中采用兩級(jí)圓錐圓柱齒輪減速器,這種方案結(jié)構(gòu)尺寸小、傳動(dòng)效率高,適合于較差環(huán)境下長期工作;方案(b)采用V帶輪傳動(dòng)和一級(jí)閉式齒輪傳動(dòng),這種方案外廓尺寸較大,有減震和過載保護(hù)作用,V帶傳動(dòng)部適合惡劣的工作環(huán)境;方案(c)采用一級(jí)閉式齒輪傳動(dòng)和一級(jí)開式齒輪傳動(dòng),成本較低,但使用壽命較短,也不適合于較差的工作環(huán)境。以上三種方案雖然都能滿足攪拌機(jī)傳動(dòng)系統(tǒng)的要求,但結(jié)構(gòu)尺寸,性能指標(biāo),經(jīng)濟(jì)性能等方面均有較大差異。結(jié)合攪拌機(jī)的各種性能要求及工作環(huán)境,最后確認(rèn)(b)方案為最終方案。2.2 電動(dòng)機(jī)選擇Y系列三相交流異步電動(dòng)機(jī)由于其有結(jié)構(gòu)簡單、價(jià)格低廉、維護(hù)方便等優(yōu)點(diǎn),故其應(yīng)用最廣,本傳動(dòng)方案的點(diǎn)擊也選用Y系列電動(dòng)機(jī)。電動(dòng)機(jī)的功率選擇是否合適,對(duì)電動(dòng)機(jī)的正常工作和經(jīng)濟(jì)性都有影響,電動(dòng)機(jī)功率的確定組要與其載荷大小、工作時(shí)間長短、發(fā)熱多少有關(guān),對(duì)于長期連續(xù)工作,載荷較穩(wěn)定的機(jī)械,根據(jù)電動(dòng)機(jī)所需的功率Pd來選擇,而不必校驗(yàn)電動(dòng)機(jī)的發(fā)熱和啟動(dòng)力矩。選擇時(shí)應(yīng)使電動(dòng)機(jī)的額定功率稍大于電動(dòng)機(jī)所需功率。由廠方提供的數(shù)據(jù)和查閱相關(guān)手冊(cè),選擇電動(dòng)機(jī)為Y200L-8攪拌軸轉(zhuǎn)速50r/minY200L-8型電動(dòng)機(jī)有關(guān)技術(shù)數(shù)據(jù)及相應(yīng)總傳動(dòng)比如下表2.1:表2.1 電機(jī)技術(shù)參數(shù)電動(dòng)機(jī)型號(hào)額定功率(kw)同步轉(zhuǎn)速r/min滿載轉(zhuǎn)速r/min總傳動(dòng)比Y200L-81575073014.6 Y200L-8型電動(dòng)機(jī):中心高:H=200mm 軸伸出部分用于裝帶輪軸段的直徑和長度為:D=55mm E=110mm鍵槽尺寸: 寬度F=16mm:深度l=6mm3 傳動(dòng)比的計(jì)算與分配3.1 計(jì)算總傳動(dòng)比 根據(jù)電動(dòng)機(jī)的滿載轉(zhuǎn)速和工作機(jī)所需轉(zhuǎn)速,按下式計(jì)算機(jī)械傳動(dòng)系統(tǒng)的總傳動(dòng)比: (3.1) 另一方面:由機(jī)械設(shè)計(jì)課程可知,機(jī)械傳動(dòng)系統(tǒng)的總傳動(dòng)系統(tǒng)的總傳動(dòng)比應(yīng)等于各級(jí)傳動(dòng)比的連乘積 即: (3.2)3.2 傳動(dòng)比的分配在設(shè)計(jì)多級(jí)傳動(dòng)的傳動(dòng)系統(tǒng)時(shí),分配傳動(dòng)比是設(shè)計(jì)中的一個(gè)重要問題。傳動(dòng)比分配得不合理,會(huì)造成結(jié)構(gòu)尺寸大,相互不協(xié)調(diào),成本高,制造和安裝不方便等。為此,根據(jù)機(jī)械手冊(cè)中的推薦值,選取帶傳動(dòng)的傳動(dòng)比, 故錐齒輪傳動(dòng)的傳動(dòng)比: (3.3)4 傳動(dòng)運(yùn)動(dòng)參數(shù)的計(jì)算 從電機(jī)到工作軸間共有一幅帶輪,兩根軸,分別為軸,軸。4.1 各級(jí)轉(zhuǎn)速令小帶輪的轉(zhuǎn)速為,軸的轉(zhuǎn)速為,軸的轉(zhuǎn)速為。 (4.1) 式中:電機(jī)的滿載轉(zhuǎn)速(r/min) 電機(jī)軸至小帶輪的傳動(dòng)比 =1 4.2 各級(jí)的輸入功率 令小帶輪的輸入功率為,軸的輸入功率為,軸的輸入功率為 (4.2) 式中:電動(dòng)機(jī)實(shí)際輸出功率 電動(dòng)機(jī)軸與小帶輪間的傳動(dòng)效率。=1 V帶傳動(dòng)效率 =0.95 =150.95=14.25kw (4.3)其中:式中:滾動(dòng)軸承傳遞效率 =0.98 錐齒輪傳動(dòng)的效率 =0.97 (7級(jí)精度) 4.3 各級(jí)轉(zhuǎn)矩 (4.4) 式中:電動(dòng)機(jī)軸的輸出轉(zhuǎn)矩: 同理可得: 5 V帶輪傳動(dòng)的設(shè)計(jì)計(jì)算5.1 設(shè)計(jì)準(zhǔn)則帶傳動(dòng)的主要失效形式為打滑和疲勞破壞。因此,帶輪傳動(dòng)的設(shè)計(jì)準(zhǔn)則為:在保證帶輪傳動(dòng)不打滑的條件下,具有一定的疲勞強(qiáng)度和壽命。5.2 原始數(shù)據(jù)及設(shè)計(jì)內(nèi)容 5.2.1 原始數(shù)據(jù): 傳遞的功率P=15kw,轉(zhuǎn)速: 5.2.2 設(shè)計(jì)內(nèi)容: 確定帶的截型、長度、根數(shù)、傳動(dòng)中心距、帶輪基準(zhǔn)直徑及結(jié)構(gòu)尺寸等。5.3 設(shè)計(jì)步驟和方法 5.3.1 確定計(jì)算功率 計(jì)算功率是根據(jù)傳遞的功率P,并考慮到載荷性質(zhì)和每天運(yùn)轉(zhuǎn)時(shí)間長短等因素的影響而確定的,即: (5.1)式中: 計(jì)算功率,單位為kw P傳遞的額定功率,單位為kw 工作情況系數(shù)由新編機(jī)械設(shè)計(jì)手冊(cè)(以下簡稱手冊(cè))表7-30查得=1.1 5.3.2 選擇帶型根據(jù)和小帶輪轉(zhuǎn)速,由手冊(cè)圖7-4,選擇帶型為:普通V帶B型。 5.3.3 確定帶輪的基準(zhǔn)直徑和1)初選小帶輪的基準(zhǔn)直徑 根據(jù)V帶截型,參考手冊(cè)表7-28,表7-22選取。為了提高V帶的壽命,宜選取較大的直徑,?。?2)驗(yàn)算帶輪的速度根據(jù)公式: 來計(jì)算帶的速度,并應(yīng)使,對(duì)于普通V帶輪經(jīng)計(jì)算得,故選取合適。 3)計(jì)算從動(dòng)輪的基準(zhǔn)直徑 (5.2) 并按V帶輪的基準(zhǔn)直徑系列表7-22,取 5.3.4 確定中心距和帶輪的基準(zhǔn)長度 由于中心距未給出,所以根據(jù)傳動(dòng)的結(jié)構(gòu)需要初定中心距,取: (5.3)計(jì)算得: 根據(jù)結(jié)構(gòu)要求取 根據(jù)帶傳動(dòng)的幾何關(guān)系,按下式計(jì)算所需要的帶輪的基準(zhǔn)長度 (5.4) 根據(jù),由手冊(cè)表7-18,查取 由于V帶傳動(dòng)的中心距一般式可以調(diào)整的,故可采用下式作近似計(jì)算,取實(shí)際中心距a: (5.5) 考慮到安裝調(diào)整和補(bǔ)償預(yù)緊力(如帶的伸長而松弛后的張緊)的需要,中心距的變動(dòng)范圍為: (5.6) (5.7) 5.3.5 驗(yàn)算主動(dòng)輪上的包角 根據(jù)對(duì)包角的要求,應(yīng)保證: (5.8) 所以:符合要求。 5.3.6 單根V帶傳遞的額定功率根據(jù)帶型、和,查手冊(cè)表7-38得: 5.3.7 確定帶的根數(shù)Z (5.9)式中:考慮包角不同德影響系數(shù),簡稱包角系數(shù),查表727得:考慮帶的長度不同時(shí)的影響系數(shù),簡稱長度系數(shù),查表731得: 單根V帶的基本額定功率。 計(jì)入傳動(dòng)比的影響時(shí),單根V帶額定功率的增量。 查表圓整取Z=5。 5.3.8 確定帶的預(yù)緊力根據(jù)公式: (5.10)其中:mV帶單位長度質(zhì)量,查表7-33得:m=0.17 6 V帶輪設(shè)計(jì)6.1 V帶輪的設(shè)計(jì)內(nèi)容 根據(jù)帶輪的基準(zhǔn)直徑和帶輪轉(zhuǎn)速等已知條件,確定帶輪的材料、結(jié)構(gòu)形式、輪槽、輪輻和輪轂的幾何尺寸、公差和表面粗糙度以及相關(guān)技術(shù)要求。6.2 設(shè)計(jì)要求設(shè)計(jì)V帶輪時(shí)應(yīng)滿足的要求有:質(zhì)量小,結(jié)構(gòu)工藝性好,無過大的鑄造內(nèi)應(yīng)力,質(zhì)量分布均勻,轉(zhuǎn)速高時(shí)要經(jīng)過動(dòng)平衡,輪槽工作面邀精細(xì)加工,以減少帶的摩損,各槽的尺寸和角度應(yīng)保持一定的精度,一使載荷分布較為均勻等。6.3 帶輪材料的選擇及結(jié)構(gòu)形式 6.3.1 材料的選擇選取大小帶輪的材料都為為HT200。 6.3.2 結(jié)構(gòu)形式V帶輪的結(jié)構(gòu)形式與基準(zhǔn)直徑有關(guān)。當(dāng)帶輪基準(zhǔn)直徑為(d為安裝帶輪的軸的直徑)時(shí),可采用實(shí)心式;當(dāng)時(shí),可采用腹板式;當(dāng),同時(shí)時(shí),可采用孔板式;當(dāng)時(shí),可采用輪輻式。所以,本傳動(dòng)方案中的大帶輪選用輪輻式,小帶輪采用實(shí)心式進(jìn)行制造。具體結(jié)構(gòu)尺寸詳見零件圖。6.4 V帶輪的輪槽圖6.1 輪槽結(jié)構(gòu)尺寸圖根據(jù)所選的帶型為普通V帶B型槽,輪槽的結(jié)構(gòu)圖如圖6.1所示。其具體的參數(shù)如表6.1所示: 表6.1 V帶輪的各種參數(shù)基準(zhǔn)寬度(節(jié)寬)14基準(zhǔn)線上槽深3.5基準(zhǔn)線下槽深10.8槽間距e第一槽對(duì)稱面至端面的距離f帶輪寬BB=(z-1)e+2f=101mm帶輪外徑帶輪節(jié)圓直徑140630中心距859.9mm帶的根數(shù)z5角度6.5 V帶輪傳動(dòng)的張緊 V帶傳動(dòng)運(yùn)轉(zhuǎn)一段時(shí)間以后,會(huì)因?yàn)閹У乃苄宰冃魏湍p而松弛。為了保證帶傳動(dòng)正常工作,應(yīng)定期檢查帶的松弛程度,采用相應(yīng)的補(bǔ)救措施。本帶輪的張緊裝置采用定期張緊,即:采用定期改變中心距地方法來調(diào)節(jié)帶的初拉力,使帶重新張緊。7 錐齒輪傳動(dòng)的設(shè)計(jì)計(jì)算7.1 選定精度等級(jí),材料及齒數(shù) 7.1.1 齒輪精度等級(jí)的選擇由于其負(fù)責(zé)將動(dòng)力輸入,并采用封閉式潤滑,故可選用7級(jí)精度。 7.1.2 材料選擇 選擇鑄鋼或鑄鐵等材料;家用及辦公用機(jī)械的功率很小,但要求傳動(dòng)平穩(wěn)、低噪音或無噪聲,以及能在少潤滑或無潤滑狀態(tài)下正常工作,因此常選用工程朔料作為齒輪材料。總之,工作條件的要求是選擇齒輪材料時(shí)首先應(yīng)考慮的因素。另外也應(yīng)考慮齒輪尺寸的大小、毛胚成形方法及熱處理和制造工藝等其他常用原則。 經(jīng)分析對(duì)比,最終選小齒輪材料為20 Cr,小齒輪調(diào)質(zhì)后表面淬火處理55HRC,大齒輪選用45剛,表面淬火處理45HRC。 7.1.3 齒數(shù)選擇 選用小錐齒輪齒數(shù)為,故大錐齒輪齒數(shù)7.2 按齒面接觸強(qiáng)度設(shè)計(jì) 由設(shè)計(jì)計(jì)算公式進(jìn)行計(jì)算,即: (7.1) 7.2.1 確定公式內(nèi)的各計(jì)算數(shù)值 1)試選載荷系數(shù) 2)計(jì)算小齒輪傳遞的轉(zhuǎn)矩: 3)選齒寬系數(shù): 4)機(jī)械設(shè)計(jì)書表10-6查取材料的彈性影響系數(shù): 5)由機(jī)械設(shè)計(jì)書中圖10-21按齒面硬度查得:小齒輪的接觸疲勞強(qiáng)度大齒輪的接觸疲勞強(qiáng)度6)由書機(jī)械設(shè)計(jì)中式 (7.2)計(jì)算應(yīng)力循環(huán)次數(shù),其中,使用壽命為10Y,一天工作12小時(shí),一年按工作300天,檢修期為3年。 7)由書機(jī)械設(shè)計(jì)中圖10-19查得: 8)計(jì)算許用應(yīng)力取失效概率為1%,安全系數(shù) S=1,有公式 (7.3) 7.2.2 計(jì)算 1)計(jì)算小齒輪代入中較小的值 2)計(jì)算: (7.4) 3)計(jì)算齒寬:b (7.5) 4)計(jì)算 b/h模數(shù): (7.6)齒高: (7.7) (7.8) 5)計(jì)算K: 根據(jù)V=0.95m/s、七級(jí)精度,查機(jī)械設(shè)計(jì) 書中圖10-8得,動(dòng)載荷系數(shù);同樣在表10-3查得:;由表10-2查得。齒向載荷分布系數(shù): 由表10-9查得: 故得: 故得出: (7.9) 6)校正分度圓直徑,公式 : (7.10) 7)計(jì)算模數(shù): (7.11)7.3 按齒根彎曲強(qiáng)度設(shè)計(jì) 設(shè)計(jì)公式為: (7.12) 7.3.1 確定公式內(nèi)的各計(jì)算數(shù)值(以下圖表均由機(jī)械設(shè)計(jì)書中查得) 1)由圖10-20查得:小齒輪 大齒輪 2)由圖10-18查得: 3)計(jì)算許用應(yīng)力: 4)計(jì)算K: 5)查?。?由表10-5查得: 6)查取應(yīng)力校正系數(shù): 由表10-5查得: 7)計(jì)算大小齒輪的 (7.12) 顯然大齒輪數(shù)值大。 小齒輪齒數(shù)計(jì)算: (7.13)大齒輪齒數(shù):經(jīng)上述設(shè)計(jì),即滿足了接觸疲勞強(qiáng)度,同時(shí)也符合齒根疲勞強(qiáng)度并做到結(jié)構(gòu)經(jīng)湊,避免浪費(fèi)。7.4 幾何尺寸計(jì)算 7.4.1 計(jì)算分度圓直徑 (7.14) 7.4.2 錐距 (7.15) 7.4.3 計(jì)算齒輪寬度 (7.15) 7.4.4錐齒輪的結(jié)構(gòu)設(shè)計(jì)經(jīng)計(jì)算、分析對(duì)比,小錐齒輪設(shè)計(jì)為齒輪軸形式,大錐齒輪設(shè)計(jì)為腹板式。參數(shù): m=3.75 i=3.28 軸的設(shè)計(jì)計(jì)算軸的結(jié)構(gòu)設(shè)計(jì)包括定出軸的合理外形和全部結(jié)構(gòu)尺寸。軸的結(jié)構(gòu)設(shè)計(jì)是根據(jù)軸上零件的安裝、定位以及軸的制造工藝等方面的要求,合理地確定軸的結(jié)構(gòu)形式和尺寸。軸的結(jié)構(gòu)設(shè)計(jì)不合理,會(huì)影響軸的工作能力和軸上零件的工作可靠性,還會(huì)增加軸的制造成本和軸上零件裝配的困難度。因此,軸的結(jié)構(gòu)設(shè)計(jì)是軸設(shè)計(jì)中的重要內(nèi)容。下面根據(jù)上述原則對(duì)軸進(jìn)行設(shè)計(jì)計(jì)算。8.1 I軸的設(shè)計(jì)計(jì)算(錐齒輪軸) 8.1.1 材料由機(jī)械零件設(shè)計(jì)手冊(cè)中的圖表查得,選用40,調(diào)質(zhì)處理,HBS=241286。, , 8.1.2 初定軸的最小直徑 根據(jù)機(jī)械設(shè)計(jì)書中表15-3,取=110 于是得: (9.1) I軸的最小直徑顯然是安裝大帶輪的直徑。 現(xiàn)取。 8.1.3 根據(jù)軸定位的要求確定軸的各段直徑和長度 現(xiàn)根據(jù)具體要求確定軸的各段直徑和長度如下圖9.1所示:圖9.1 小錐齒輪圖 8.1.4 小錐齒輪的受力分析圓周力: (9.2)徑向力: (9.3)軸向力: (9.4)法向載荷: (9.5) 8.1.5 鍵的校核 選用A型普通鍵,軸鍵、輪轂的材料都用20剛。 取L=80mm (9.6) (9.7) 式中:T傳遞的轉(zhuǎn)矩; K鍵與輪轂、鍵槽的接觸高度 K=0.5h=7 l鍵的工作長度:l=L-b=58mm; d軸的直徑; 8.1.6 I軸軸承的校核(30212) 查手冊(cè)有:C=102000N; ; Y=1.5; e=0.4; 圖9.2 軸的受力圖(1)求軸承的載荷(如上圖9.2)已知: 故得徑向載荷: 軸向力: 與同向且所以指向軸承1.即軸承1為緊端,軸承2為松端。故有: (2)求軸承當(dāng)量動(dòng)載荷 由機(jī)械設(shè)計(jì)手冊(cè)中表13-6查得: (3)求軸承的壽命 (9.8) 故所選軸承可用。 8.1.7 軸上載荷的計(jì)算圖9.3 軸的受力及彎扭圖 由圖9.3彎矩和扭矩圖可以看出截面B是軸的危險(xiǎn)面,將計(jì)算出的截面B處的、及M列如下表9.2:表9.2 截面B處的彎矩表載荷水平面H垂直面V支反力F彎矩總彎矩扭矩 8.1.8 按彎扭合成應(yīng)力校核軸的強(qiáng)度 (9.9) 式中:W軸的抗彎截面系數(shù): 對(duì)稱循環(huán)應(yīng)力的軸的許用應(yīng)力:MPa 軸的計(jì)算應(yīng)力:Mpa 軸所受彎矩: 軸所受的扭矩:有相關(guān)資料查得: ;。所以 所以所設(shè)計(jì)的軸符合強(qiáng)度要求。8.2 II軸的設(shè)計(jì)計(jì)算 8.2.1 材料 選用45鋼,調(diào)質(zhì)處理,HBS=217255; 8.2.2 初定最小直徑 取 (9.10)II軸的最小直徑是安裝聯(lián)軸器的直徑 8.2.3 聯(lián)軸器的選擇 計(jì)算轉(zhuǎn)矩: (9.11)查表14-1得 選取聯(lián)軸器型號(hào): 8.2.4 根據(jù)軸的定位要求,確定各段直徑和長度 現(xiàn)根據(jù)具體要求確定軸的各段直徑和長度如下圖9.4所示:圖9.4 軸的尺寸圖 8.2.5 大錐齒輪軸的受力分析 圓周力: 徑向力: 軸向力: 8.2.6 鍵的校核 材料均選用20鋼 II1鍵的型號(hào): GB/T1096 II2鍵的型號(hào): GB/T1096校核公式: (9.12) 其中:; ; ; ; ; ; 故鍵II1能用; 故鍵II2能用; 8.2.7 軸承的校核(32218) 已知: C=270000N;Y=1.4;e=0.42 ;圖9.5 軸承的受力分析圖 (1)軸承的徑向力: 軸向力: 由于與同向且 所以指向軸承2,即軸承1為松端,軸承2為緊端。 故有: (2)求軸承的當(dāng)量動(dòng)載荷 由機(jī)械設(shè)計(jì)手冊(cè)中表13-6查得: (3)求軸承的壽命 故 所選軸承可用。 8.2.8 軸上載荷的計(jì)算圖9.6 軸的受力及彎矩圖由圖9.6彎矩圖和扭矩圖看出,截面B為軸的危險(xiǎn)截面,將計(jì)算出的截面B處的、及M列如下表9.3:表9.3 截面B處彎矩表載荷水平面H垂直面V支反力F 彎矩 總彎矩扭矩 8.2.9 按彎扭合成應(yīng)力校核軸的強(qiáng)度 (9.13) 式中: W軸的抗彎截面系數(shù); 對(duì)稱循環(huán)應(yīng)力的軸的許用應(yīng)力;MPa 軸的計(jì)算應(yīng)力;Mpa 軸所受彎矩; 軸所受的扭矩;有相關(guān)資料查得: ;。所以 所以所設(shè)計(jì)的軸符合強(qiáng)度要求。9 結(jié)論與展望通過這次畢業(yè)設(shè)計(jì),集中、綜合從不同的知識(shí)方位對(duì)以前所學(xué)知識(shí)進(jìn)行了一次大的回顧和訓(xùn)練,是一次四年積累的厚積薄發(fā)、一一展示,對(duì)我們以后的學(xué)習(xí)和工作將起到積極而有深遠(yuǎn)的影響。本次畢業(yè)設(shè)計(jì)的題目為無軸攪拌機(jī)傳動(dòng)部件的設(shè)計(jì)。首先對(duì)傳統(tǒng)的幾種常見的攪拌機(jī)構(gòu)進(jìn)行分析、總結(jié)其工作原理及其存在的常見問題。了解目前對(duì)其存在的問題的常用解決方案。熟悉“無軸”攪拌理念,掌握無軸攪拌機(jī)的工作原理,然后將其與傳統(tǒng)的攪拌機(jī)進(jìn)行比較,分析其主要優(yōu)點(diǎn)及可能存在的問題以及解決方案。通過分析我們知道了,目前市場使用的攪拌機(jī)都存在著“包軸”的現(xiàn)象,雖然也出現(xiàn)如論文前所述的各種解決方案,但由于其都有一根貫穿整個(gè)攪拌部件的軸存在,所以無論如何改進(jìn)也無法完全消除“包軸”現(xiàn)象。而新型開發(fā)的無軸攪拌機(jī)正是彌補(bǔ)了這一缺陷。真正做到了無“包軸”現(xiàn)象。其次,這次設(shè)計(jì)的重點(diǎn)是對(duì)其傳動(dòng)部件的設(shè)計(jì)計(jì)算,在設(shè)計(jì)過程中,在查閱資料的同時(shí),運(yùn)用以前所學(xué)知識(shí),對(duì)傳動(dòng)方案進(jìn)行了不同方案的比較,從中選定了最優(yōu)的工藝方案,其中也不乏對(duì)知識(shí)的綜合運(yùn)用,這時(shí)才感覺到傳動(dòng)方案的選擇在機(jī)械傳動(dòng)中的重要性,它可以最大限度上節(jié)省生產(chǎn)成本,提高企業(yè)經(jīng)濟(jì)效益,在競爭中處于有利地位、立于不敗之地。所以要振興我國的機(jī)械制造業(yè),必須從最基礎(chǔ)的東西做起,從機(jī)械產(chǎn)品的生產(chǎn)、設(shè)計(jì)過程中各個(gè)環(huán)節(jié)最大程度地減少成本。我采用的是帶輪加錐齒輪的減速機(jī)構(gòu),即利用了帶輪的傳動(dòng)遠(yuǎn)距離傳動(dòng)、大傳動(dòng)比,又利用了錐齒輪傳動(dòng)可改變傳動(dòng)方向的優(yōu)點(diǎn)。通過設(shè)計(jì)計(jì)算達(dá)到了即提高工作效率又能有效地節(jié)約能源的目的。無軸攪拌機(jī)是一種新生產(chǎn)品,故必存在了其產(chǎn)品不成熟的一面,要想真正做到利國利民,在激烈的市場競爭中立于不敗,就必須對(duì)其各個(gè)方面進(jìn)行改進(jìn)和優(yōu)化,本論文只是對(duì)其中的傳動(dòng)部分進(jìn)行了設(shè)計(jì)改良,在今后的研究中還應(yīng)注重其它方面的改進(jìn)??傊@次畢業(yè)設(shè)計(jì)從各個(gè)方面培養(yǎng)了我獨(dú)立思考、獨(dú)立發(fā)現(xiàn)問題和解決問題的習(xí)慣和素養(yǎng),這在以后的工作中將受益匪淺。致 謝本文是在韓邦華導(dǎo)師的悉心指導(dǎo)下完成的,他嚴(yán)謹(jǐn)?shù)淖黠L(fēng)一直是我工作、學(xué)習(xí)中的榜樣;在整個(gè)論文選題、傳動(dòng)方案設(shè)計(jì)、計(jì)算,到學(xué)位論文撰寫,都是老師及時(shí)給予我建議,指出不足之處,幫助我更好地組織論文結(jié)構(gòu),不斷充實(shí)論文的內(nèi)容鼓勵(lì)支持完成的。在此,我對(duì)導(dǎo)師付出的心血和汗水表示由衷的感謝!在做論文期間,由于本人才疏學(xué)淺,加之此次設(shè)計(jì)時(shí)間緊任務(wù)重,老師以及我們組的其他成員都積極、熱情的幫我,對(duì)我的工作、學(xué)習(xí)和生活給予了許多無私的關(guān)心與幫助,使我的論文得以順利完成,由于篇幅限制在此不再將他們一一列舉,但是我對(duì)他們無私慷慨的幫助表示深深的謝意!謹(jǐn)以此文,向所有關(guān)心、支持和幫助過我的老師、同事、同學(xué)、朋友和家人致以最誠摯的謝意!參考文獻(xiàn)1 張黎驊.新編機(jī)械設(shè)計(jì)手冊(cè)M.北京:人民郵電出版社,2008.5.2 成大先.機(jī)械設(shè)計(jì)手冊(cè)(單行本)減(變)速器.電機(jī)與電器M.北京:化學(xué)工業(yè)出社, 2004.1.3 簡明機(jī)械設(shè)計(jì)手冊(cè)M.同濟(jì)大學(xué)出版社,2002.5.4 董懷武.畫法幾何及機(jī)械制圖M.武漢理工大學(xué)出版社,2000.11.5 馮忠緒.混凝土攪拌理論與設(shè)備M.北京:人民交通出版社,2001.6 濮良貴.機(jī)械設(shè)計(jì)M.北京:高等教育出版社.2007.7 陸 玉.機(jī)械設(shè)計(jì)課程設(shè)計(jì)M.機(jī)械工業(yè)出版社,2006.12.8 J.Marchan、H.Homain.S.Diamond. M.Pigeon and H.Guiraud. THEMICROSTRUCTURE OF DRY CONCRETE PRODUCTSM. Cement and Concrete Research.1996,Vol.26 No.39 魏覺.JS型混凝土攪拌機(jī)功率計(jì)算及結(jié)構(gòu)設(shè)計(jì)J.工程機(jī)械,1991.5,第5期:25-60.10 Saeed, Khalaf, Rejeb. IMPROVING COMPRESSIVE STRENGTH OF CONCRETE BY A TWO-STEP MIXING METHODM. Cement and Concrete Research. 1996, Vo1.26 No.4.11 中華人民共和國國家標(biāo)準(zhǔn)混凝土攪拌機(jī)(GB/T9142-2000)M.北京:中國標(biāo)準(zhǔn)出版,2000.12 趙利軍.雙臥軸攪拌機(jī)參數(shù)優(yōu)化及其試驗(yàn)研究A.西安:長安大學(xué)碩士學(xué)位論文C. 2002.5.13 龔鐵平編譯.國外混凝土機(jī)械M.北京:中國建筑工業(yè)出版社,1983.14 龔溎義.機(jī)械設(shè)計(jì)課程設(shè)計(jì)圖冊(cè)M.高等教育出版社,2007.5.15 程福.機(jī)械專業(yè)英語M.大連理工大學(xué)出版社,2009.7.16 黃健求. 機(jī)械制造技術(shù)基礎(chǔ)第二版M. 北京:機(jī)械工業(yè)出版社.17 黃如林,汪群. 金屬加工工藝及工裝設(shè)計(jì)M.北京:化學(xué)工業(yè)出版社,2006.18 Maassen F . Et al. Analytical and EmpirialA. Methods for Optimization of Cylinder Liner Bore Distorton C . SAE: 2001-01-05:16-39.35無錫太湖學(xué)院 信 機(jī) 系 機(jī)械工程及自動(dòng)化 專業(yè)一、 題目及專題1、 題目 無軸攪拌機(jī)傳動(dòng)系統(tǒng)的設(shè)計(jì) 2、 專題 二、 課題來源及選題依據(jù)參考現(xiàn)場實(shí)際生產(chǎn),要求學(xué)生能夠結(jié)合無軸攪拌機(jī)的工作原理和過程,針對(duì)實(shí)際使用過程中存在的攪拌阻力、攪拌空間、能耗等問題,綜合所學(xué)的機(jī)械原理、機(jī)械設(shè)計(jì)以及機(jī)電傳動(dòng)等知識(shí),對(duì)攪拌機(jī)的無軸工作進(jìn)行改進(jìn)設(shè)計(jì),使其在工作過程中真正達(dá)到提高效率,節(jié)約能源的效果。 改進(jìn)過程中,在滿足產(chǎn)品工作要求的情況下,應(yīng)盡可能多的采用標(biāo)準(zhǔn)件,提高其互換性要求,以減少產(chǎn)品的設(shè)計(jì)生產(chǎn)成本。 三、 本設(shè)計(jì)(論文或其他)應(yīng)達(dá)到的要求1、 該部件工作時(shí),能運(yùn)轉(zhuǎn)正常;2、 熟悉有關(guān)標(biāo)準(zhǔn)、規(guī)格、手冊(cè)和資料的應(yīng)用; 3、 擬定工作機(jī)構(gòu)和傳動(dòng)系統(tǒng)的運(yùn)動(dòng)方案,并進(jìn)行多方案對(duì) 分析;4、 對(duì)無軸攪拌機(jī)傳動(dòng)系統(tǒng)具有初步分析能力和改進(jìn)設(shè)計(jì)的能 力; 5、 理論聯(lián)系實(shí)際的工作方法和獨(dú)立工作能力深化和提高; 6、設(shè)計(jì)繪制零件工作圖若干; 7、編制設(shè)計(jì)說明書1份。 四、 接受任務(wù)學(xué)生: 機(jī)械97 班 姓名 龍躍 五、 開始及完成日期:自2012年11月12日至2013年5月25日六、 設(shè)計(jì)(論文)指導(dǎo)(或顧問): 指導(dǎo)教師 簽名 簽名 簽名 教研室主任 科學(xué)組組長 簽名 系主任 簽名 2012年11月12日I英文原文:Designing and Modeling a Torque and Speed Control Transmission (TSCT)1 Background The Partnership for a New Generation of Vehicles (PNGV) was formed between the Federal Government, Ford Motor Company, General Motors Corporation, and Chrysler Corporation. The goal of this partnership was to allow the major U.S. automotive manufactures to collaborate with each other and produce high fuelefficiency, low emissions vehicles for sale to the general public. The performance objective for these manufacturers was to create mid-sized passenger cars capable of attaining an 80 mpg (gasoline) composite fuel economy rating on the Environmental Protection Agency (EPA) city and highway cycles. Hybrid vehicle technology has shown great promise in attaining the goals set forth by the PNGV. Hybrid electric vehicles (HEVs) employ technology that helps bridge the gap between the future hope of an electric vehicle (EV) and todays current vehicles. Within the past year hybrid electric vehicles have gained an important place in the vehicle market. American Honda Motor Company, Inc. is currently releasing their first generation HEV, the Insight. The Insight is a compact, two passenger, parallel HEV which achieves more than 65 mpg (composite) on the EPA test cycles: the highest of any production vehicle ever tested. Toyota Motor Corporation has also released a hybrid vehicle for sale to the general public. The Toyota Prius is currently for sale in Japan and will come the United States in the beginning of the year 2000. The Prius is a four passenger combination hybrid employing an a gasoline engine, high power electric motor, and an electromechanical continuously variable transmission (CVT) comprised of a planetary geartrain and a high power alternator/motor. It is through technology incorporated in vehicles such as the Prius that automotive transmission design and operation will make significant new advances. 1.1 Current Automotive Transmission Technologies With the advent of the automobile also came the creation of the automotive transmission. Early vehicles were simple with manual controls for all functions including the transmission. As advances have been made in vehicles over the past several decades, transmission technology has also advanced. The automatic transmission has nearly replaced the manual transmission in all but economy and performance cars. This trend can be attributed to ease of use, higher power engines becoming available, and congestion in urban areas. Another new transmission technology beginning to see application particularly in foreign markets is the continuously variable transmission that offers continuous operation without shifting between a high and low gear ratio. These three types of transmissions are all similar in function though their objectives are accomplished in different ways. The capabilities of these transmissions are limited to decoupling the engine speed from the speed of wheels and thereby providing one of several forward or reverse gear ratios. Each transmission is also a single input (engine) and single output (drive device). There are typically no provisions for attaching multiple power sources or for extracting power from more than one point. The exception to this is heavy-duty transmissions equipped with provisions for a power take off for driving auxiliary mechanical equipment. Single input, single output operation limits drivetrain flexibility for newer systems employing multiple power sources such as those used in the next generation of hybrid vehicles. 1.1.1 Manual Transmission Operation Manual transmissions are the least complex and oldest design of power transmission available. In simplest form, a manual transmission is a linear combination of a clutch and a directly geared connection. More sophisticated examples rely on this design but add the ability to select other gear ratios to allow different output speeds for the same input speed. Of these types of transmissions, there are two variations: synchronized and unsynchronized. Synchronized manual transmissions are typically used for light duty applications. Coupled to each gear is a synchronizer that allows the operator to disengage the clutch and select whatever gear necessary. The selection of a different gear engages the synchronizer, which then matches engine input speed and transmission output speed before the gears are engaged. Unsynchronized manual transmissions are more robust by nature. The operator must double-clutch between shifts to match engine and transmission speed manually. However, this allows a transmission of a given size to handle greater load as space previously occupied by the synchronizers can now be dedicated to the use of wider gears. Applications of these types of manual transmissions are for over-the-road trucks and up to larger equipment with total vehicle weights over 100 tons. 1 1.1.2 Automatic Transmission Operation Automatic transmissions are a complex assembly of many components that allow for seamless power transmission. Those currently available in production vehicles use torque converters, clutches, and planetary gear sets for the selection of different output ratios. The engine is connected to the torque converter that acts very much like a clutch under some conditions while more like a direct connection in others. The torque converter is a hydraulic coupling that will slip under light load (idle), but engage progressively under higher load. While the torque converter transmits power to the transmission there is a speed reduction across the unit during low speed operation. This reduction is typically between 2.5:1 to 3.5:1. Once higher vehicle speeds are attained, the torque converter input and output may be locked together to achieve a direct drive though the unit. The output of the torque converter is typically connected to a hydraulic pump that provides the necessary pressure to engage different clutches within the transmission and the planetary drive. Different gear ratios are created through the use of two or more planetary gearsets. These gearsets are combined with clutches on different elements. By clutching and declutching different elements, multiple gear ratios are possible. Basic automatic transmissions are equipped with a single control input that is throttle position. The combination of this with the hydraulic pressure created within the transmission allows for mechanical open loop control of all gear selections. Newer variations of the automatic transmission are equipped with electronic feedback controls. Shift logic is dependent on many more variables such as engine speed, temperature, current driving trend, throttle position, vehicle accelerations, etc. This allows the transmission controller to monitor vehicle operation and using a rule-based control strategy decide which gear is best suited to the current driving conditions. Newer systems are also integrated with the engine controller such that a vehicle control computer has authority over engine and transmission operation simultaneously. This allows for such features as increasing engine speed during high-speed downshifts to match engine and transmission speed for smoother shifting and retarding fueling and ignition timing during high power upshifts to reduce jerk. Previously, transmissioncontrol was much simpler because overrunning clutches were employed in higher gears that only allowed for coasting to conserve fuel. 1 1.1.3 Continuously Variable Transmission Operation Continuously variable transmissions are one of the emerging transmission technologies of the last twenty years. This type of transmission allows power transmission over a given range of operation with infinitely variable gear ratios between a high and low extreme. These transmissions are constructed using two variable diameter pulleys with a belt connecting the two. As one pulley increases in size, the other decreases. This is accomplished by locating on one shaft a stationary sheave and a movable sheave. For automotive applications, a hydraulic actuator controls movement of the sheave. However, centrifugal systems along with high power electronic solenoids may be used. A second shaft in the CVT contains the other stationary sheave and movable sheave also controlled hydraulically. A flexible metal belt is fitted around these two pulleys and the movable sheaves are located on opposite sides of the belt. There are two variations of this type of transmission: push belt and pull belt. Pull belt CVTs were the first type to be manufactured due to simplicity. A clutch is attached between the first pulley and the engine while the output of the second pulley was connected to a differential and thus the wheels. A hydraulic pump is used to control the diameter of the two different pulleys. As power is applied the first pulley creates a torque that is transmitted through the belt (under tension) to the second pulley. Control of the transmission ratio is usually a direct relationship dependent upon throttle position. Push belt CVTs, similar in design to the Van Doorne, are much the same as pull belt CVTs, except that power is transmitted through the belt while under compression. This provides a higher overall efficiency due to the belt being pushed out of the second pulley and lowering frictional losses. Current work with these transmissions is being focused on creating larger units capable of handling more torque. Efficiency of the CVT is directly related to how much tension is in the belt between the two pulleys. CVT torque handling capacity increases as tension in the belt increases. However, this increased tension lowers power transmission efficiency. The belt must slide across the faces of each pulley as it enters and exits upon each half rotation. This sliding of the belt creates frictional losses within the system. In addition, there may be significant parasitic losses associated with raising the hydraulic pressure required to move or maintain the position of the sheaves in each pulley. 2 1.1.4 Automatically Shifted Manual Transmission Operation Automatically shifted manual transmissions are a fairly recent innovation. The benefit of the manual transmission is that (due to the direct mechanical connection through fixed gears) efficiency is very high. The drawback is that there must be some interaction with the user in the selection and changing of gears. Automatically shifted manuals were created to address this issue. These types of transmissions are traditionally synchronized manual transmissions with the addition of automation of the gear selection and control of the clutch. A logic controller is also employed to decide when and how to shift. Automatic shifting is usually accomplished through the use of electro-hydraulics. A high-pressure electric pump supplies pressure to hydraulic solenoids that are used to shift the transmission. A hydraulic ram is also used to engage and disengage the clutch. Current versions of these transmissions also employ unsynchronized gears. This allows for overall smaller packaging to accomplish the same task. Input speed of the engine is monitored along with layshaft speed. When a gear change is initiated, the controller opens the clutch, shifts to the desired gear while matching engine and lay shaft speed, and then closes the clutch again. This shifting operation can all be achieved in less than one third of a second. Automatically shifted manual transmissions shift gears faster than humanly possible. 3 1.1.5 Manually Shifted Automatic Transmission Operation Manually shifted automatic transmissions are a variation on control of the transmission. The user is allowed to select either automatic or manual shifting modes. During automatic mode, the transmission functions identically to an automatic transmission. While in manual shift mode however, the transmission controller allows the user full authority over gear changes as long as the gear change will not overspeed the engine. This mode of operation traditionally offers the user tighter, more positive shift feel. The only requirement of an automatic transmission for manual shifting is that shifts must be accomplished rapidly enough to allow the user a feeling of fluidity. The act of shifting must provide the immediate desired response. 3 1.1.6 Planetary Gear Drive Transmission Operation Planetary gear sets are unique in that the combination of gears creates a twodegree-of-freedom system. The gear sets are comprised of a ring gear, a sun gear in the center, and planetary gears that contact both the ring and the sun gears. Motion of the planetary gears is controlled by the carrier on which each of the planetary gears rotate. The carrier maintains the position of the planets in relation to each other but allows rotation of all planets freely. Inputs (or outputs) to the gear train are the ring gear, sun gear, and planetary carrier. By prescribing the motion of any two of these parameters, the third is fixed in relation to the other two. By employing one planetary geartrain, a fixed ratio between input and output is created. Increasing or decreasing the number of teeth on the sun and ring gears can change this ratio. This in turn changes the number of teeth on the planetary gears, which has no other effect as these gears act as idlers. When combining more than one planetary gear train at one time, braking or allowing the movement of different elements can create a wide range of effective operation in terms of relative speeds, torque transfer, and direction of rotation. This is the type of system that is used in automatic transmissions described above. These systems are also employed in large stationary power transmission applications. 1 1.2 Current Hybrid Electric Vehicle Transmission Design Hybrid vehicles are vehicles that utilize more than one power source. Current propulsion technologies being favored are compression ignition (CI) engines, spark ignition(SI) engines, hydrogen-fueled engines, fuel cells, gas turbines, and high power electric drives. Energy storage devices include batteries, ultra-capacitors, and flywheels. Hybrid powertrains can be any combinations of these technologies. The aim of these vehicles is to use cutting edge technology combined with current mass-produced components to achieve much higher fuel economy combined with lower emissions without raising consumer costs appreciably. These vehicles are targeted to bridge the gap between current technology and the future hope of a Zero Emission Vehicle (ZEV), presumably a hydrogen-fueled fuel cell vehicle. The operation of these systems must also be transparent to the user to enhance consumer acceptability and the vehicle must still maintain all required safety features with comparable dynamic performance all at an acceptable cost. By combining multiple power sources, overall vehicle efficiency can be improved by the ability to choose the most efficient power source during the given operating conditions. This is key in improving vehicle efficiency because current battery technology dictates that nearly all total energy used by the vehicle across a reasonable range of driving comes from the on-board fuel. Highly adaptive control strategies that may be employed in the next generation of HEVs may monitor vehicle speed, desired torque, energy available, and recent operating history to choose which mode of operation is most beneficial. These advanced control schemes will maximize the usage of the fuel energy available by choosing the most efficient means of power delivery at any instant. The reduced usage of energy for a given amount of work may also result in lower exhaust emissions due to a reduction in fuel energy used. 1.2.1 The Advantages and Disadvantages of Series Hybrid Vehicles Series hybrid vehicles typically have an internal combustion engine (ICE) that iscoupled directly to an electric alternator. The vehicle final drive is supplied entirely by an electric traction motor that is supplied energy by the battery pack or combination of engine and alternator. The benefit of this type of operation is the engine speed and torque are decoupled from the instantaneous vehicle load and the engine needs only to run when battery state of charge (SoC) has dropped below some lower level. This allows engine operation to be optimized for both fueling and ignition timing in the case of a spark ignited engine, or fueling and injection timing for a compression ignition engine. The engine is also operated in the most efficient speed and torque without encountering transient operation regardless of load. The result is excellent fuel economy and low emissions. Series HEV operation is exceptionally well suited to highly transient vehicle operation which is prevalent in highly urban areas and city driving. The disadvantage to series hybrid operation is the efficiency losses associated with converting mechanical to electrical and then electrical to mechanical energy. Further losses in system efficiency are realized when the energy is stored in the battery pack for later use. Only a fraction of the energy put into the batteries can be returned due to the internal resistance of the batteries. The mechanical energy of the engine is directly converted to electricity by an alternator that has losses both in internal resistance and eddy currents present. Further losses are incurred when this electrical energy is converted back to mechanical energy by the traction motor and controller. Dynamic performance is also limited, as the engine cannot supplement the traction motor in powering the vehicle. 1.2.2 The Advantages and Disadvantages of Parallel Hybrid Vehicles Parallel systems also employ two power sources, typically an engine and a traction motor with both directly coupled to the wheels typically through a multi-speed transmission. This requires that the engine see substantial transient operation. However, the motor can act as a load-leveling device allowing the engine to operate in a more efficient operating region. When the vehicle is operating in a low load state the engine can be decoupled from the drivetrain and shut off, or the motor can be used to charge while driving creating a greater power demand for the engine and storing energy in the battery pack. The disadvantage of parallel hybrids is that direct connection of the engine to the wheels requires transient engine operation. This operation lowers fuel economy and increases exhaust emissions especially when employing SI engines. Ignition timing and fueling cannot be optimized for a single region of operation either. However, dynamic performance of parallel hybrids is much better than that of series hybrids using the same components. Much more power is available as both the engine and motor can provide power to the wheels simultaneously. These characteristics lend parallel HEVs to excel in higher load, less transient situations and when using high efficiency engines such as CI engines. 1.2.3 The Advantages and Disadvantages of Combination Hybrid Vehicles The third variation of hybrid vehicle drivetrains is the combination, which is a system that can function both as a series and parallel hybrid. Complex combinations of engines, alternators, and motors can accomplish this with geared connections and multiple clutches. By clutching and declutching different elements, a combination can be designed to function as a series hybrid under low speed transient conditions and then as a parallel hybrid under higher speed and load. This allows for increased efficiency as each mode of operation is employed under the ideal operating conditions. Drawbacks to these systems are increased mechanical and drivetrain control complexity along with higher weight associated with more components. Controlling these types of systems is much more
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