三軸四擋低速載貨汽車變速器的設(shè)計(jì)【全套含20張CAD圖紙】

資源目錄里展示的全都有預(yù)覽可以查看的噢，，下載就有,,請(qǐng)放心下載，原稿可自行編輯修改=【QQ：11970985 可咨詢交流】====================喜歡就充值下載吧。。。資源目錄里展示的全都有，，下載后全都有,,請(qǐng)放心下載，原稿可自行編輯修改=【QQ：197216396 可咨詢交流】==================== 附件1 鹽城工學(xué)院優(yōu)秀畢業(yè)設(shè)計(jì)（論文）推薦表 院（系）名稱：機(jī)械工程學(xué)院 填表日期： 年6月20日 學(xué)生 姓名 入學(xué) 年級(jí) 指導(dǎo)教師 畢業(yè)設(shè)計(jì)（論文）總周數(shù) 14 姓名 專業(yè)技術(shù)職務(wù) 年齡 所在單位 李書偉 高級(jí)工程師 40 機(jī)械工程學(xué)院 畢業(yè)設(shè)計(jì)（論文）題目 低速載貨汽車變速器的設(shè)計(jì) 畢業(yè)設(shè)計(jì)（論文）主要涉及研究方向 1、 參與總體設(shè)計(jì)； 2、 變速器結(jié)構(gòu)型式分析和主要參數(shù)的確定； 3、 變速器結(jié)構(gòu)設(shè)計(jì)； 4、 用AUTOCAD繪制二維工程圖。 畢業(yè)設(shè)計(jì)（論文）選題依據(jù)及背景 根據(jù)專業(yè)方向和畢業(yè)設(shè)計(jì)要求，從國(guó)家“三農(nóng)”和汽車產(chǎn)業(yè)政策出發(fā)，盡量結(jié)合工程生產(chǎn)實(shí)際，依據(jù)相關(guān)國(guó)家或行業(yè)標(biāo)準(zhǔn)。 學(xué)校中期檢查情況 畢業(yè)設(shè)計(jì)（論文）的水平與特色 方案正確，分析合理，工藝可行，具有實(shí)用價(jià)值。 典型輕型貨車NJ130系列的變速器齒輪大多采用非標(biāo)準(zhǔn)齒輪，本次設(shè)計(jì)的變速器齒輪等零部件貫徹了國(guó)家或行業(yè)的最新標(biāo)準(zhǔn)，具有較好的加工和使用性能，結(jié)構(gòu)緊湊、使用維修方便，并可附裝取力機(jī)構(gòu)供用戶的特殊需要。 畢業(yè)設(shè)計(jì)（論文）有何實(shí)驗(yàn)、實(shí)踐或?qū)嵙?xí)基礎(chǔ) 到相關(guān)企業(yè)進(jìn)行參觀實(shí)習(xí)，努力保證設(shè)計(jì)實(shí)際可行。 學(xué)生畢業(yè)設(shè)計(jì)（論文）期間的研讀書目 [1] GB7258-2004，機(jī)動(dòng)車運(yùn)行安全技術(shù)條件[S]. [2] GB18320-2001，農(nóng)用運(yùn)輸車安全技術(shù)條件[S]. [3] 王望予.汽車設(shè)計(jì)[M].北京：機(jī)械工業(yè)出版社，2000. [4] 劉惟信.汽車設(shè)計(jì)[M].北京：清華大學(xué)出版社,2001. [5] 陳家瑞.汽車構(gòu)造.（下冊(cè)）[M].北京：機(jī)械工業(yè)出版社，2005. [6] 汽車工程手冊(cè)編輯委員會(huì).汽車工程手冊(cè)（設(shè)計(jì)篇）[M].北京：人民交通出版社,2001. [7] 余志生.汽車?yán)碚揫M].北京：機(jī)械工業(yè)出版社，2004. [8] QC/T580-1999，汽車變速器安裝尺寸[S]. [9] 汽車工程手冊(cè)編輯委員會(huì).汽車工程手冊(cè)（制造篇）[M].北京：人民交通出版社,2001. [10] 沈世德.機(jī)械原理[M].北京：機(jī)械工業(yè)出版社，2002. [11] 徐錦康.機(jī)械設(shè)計(jì)[M].北京：高等教育出版社，2004. [12] 成大先.機(jī)械設(shè)計(jì)手冊(cè)（1～4冊(cè)）[M].北京：化學(xué)工業(yè)出版社，1993. [13] 席新明.四輪農(nóng)用運(yùn)輸車使用維修圖解[M].鄭州：河南科學(xué)技術(shù)出版社，2002. 指導(dǎo)教師評(píng)語(yǔ)及推薦意見（包括學(xué)生的工作態(tài)度、知識(shí)與能力、成果與水平、設(shè)計(jì)（論文）質(zhì)量等幾方面） 該生設(shè)計(jì)期間出勤率高，學(xué)習(xí)態(tài)度端正，工作努力、嚴(yán)謹(jǐn)、踏實(shí)；較好地進(jìn)行文獻(xiàn)查閱、資料收集；提出合理的實(shí)施方案，進(jìn)行設(shè)計(jì)與計(jì)算，并不斷改進(jìn)，精益求精，按要求完善，圓滿完成規(guī)定任務(wù)；綜合運(yùn)用知識(shí)能力較強(qiáng)；方案可行，計(jì)算正確規(guī)范且完整，成果質(zhì)量水平較好。 指導(dǎo)教師簽字： 年 月 日 指導(dǎo)教師對(duì)申報(bào)材料真實(shí)性的意見 申報(bào)材料真實(shí)可靠。 指導(dǎo)教師簽字： 年 月 日 院(系) 推薦意見 院(系)公章 年 月 日 注：專業(yè)代碼和專業(yè)名稱應(yīng)按教育部公布的專業(yè)目錄填寫。 現(xiàn)設(shè)的相應(yīng)專業(yè)名稱如與之不同，請(qǐng)?jiān)凇皞渥ⅰ睓谥凶⒚鳌? 低速載貨汽車變速器的設(shè)計(jì)0低速載貨汽車變速器的設(shè)計(jì)低速載貨汽車變速器的設(shè)計(jì) 摘摘 要：要：課題來源于生產(chǎn)實(shí)際，依據(jù)機(jī)動(dòng)車安全技術(shù)條件和汽車機(jī)械變速器總成技術(shù)條件 ，針對(duì)低速載貨汽車的運(yùn)行特點(diǎn)而設(shè)計(jì)。參與了汽車的總體設(shè)計(jì)，確定了汽車的質(zhì)量參數(shù)，選擇了合適的發(fā)動(dòng)機(jī)，并且計(jì)算出汽車的最高速度。關(guān)于變速器的設(shè)計(jì)，首先選擇標(biāo)準(zhǔn)的齒輪模數(shù)，在總檔位和一檔速比確定后，合理分配變速器各檔位的速比，接著計(jì)算出齒輪參數(shù)和中心距，并對(duì)齒輪進(jìn)行強(qiáng)度驗(yàn)算，確定了齒輪的結(jié)構(gòu)與尺寸，繪制出所有齒輪的零件圖。根據(jù)經(jīng)驗(yàn)公式初步計(jì)算出軸的尺寸，然后對(duì)每個(gè)檔位下軸的剛度和強(qiáng)度進(jìn)行驗(yàn)算，確定出軸的結(jié)構(gòu)和尺寸，繪制出各根軸的零件圖。根據(jù)結(jié)構(gòu)布置和參考同類車型的相應(yīng)軸承后，按國(guó)家標(biāo)準(zhǔn)選擇合適的軸承，然后對(duì)軸承進(jìn)行使用壽命的驗(yàn)算，最終完成了變速器的零件圖和裝配圖的繪制。此變速器的齒輪都為標(biāo)準(zhǔn)齒輪，檔位數(shù)和傳動(dòng)比與發(fā)動(dòng)機(jī)參數(shù)匹配，保證了汽車具有良好的動(dòng)力性和經(jīng)濟(jì)性。該變速器具有操縱簡(jiǎn)單、方便、傳動(dòng)效率高、制造容易、成本低廉、維修方便的特點(diǎn)，適合低速載貨汽車的使用。關(guān)鍵詞：關(guān)鍵詞：低速載貨汽車；變速器；設(shè)計(jì)Abstract: The topic comes from the production reality, which is based on the safety specifications for power driven vehicles operating on roads and the specifications for the automobile mechanical transmission. It designs the low-speed trucks movement characteristic. The automobile quality parameters are determined, according to the automobile system design, choosing the appropriate engine, and calculating the maximum speed. When design the transmission, first, we choose the standard gear modulus and determine all speeds proportions after we choose the number of the transmissions gears and the first gear, then calculate the gears parameter and the center distance, and the gear needs the intensity checking calculation. We determine gears structure, then complete drawing of the gears component. According to the empirical formula, we preliminary carry on the checking calculation to each gears rigidity and the intensity to determine the axis structure and size, and thus draw up various axis component drawing. After arranged structure and compared with the similar type of vehicles bearing, according to the national standard, we select the appropriate bearings, and then calculate the service life of the bearings. Finally drawing of the component and the assembly of the transmission are completed. Because the transmission gear is the standard gear and the number of gears and speeds proportions match to the engine conditions, which ensure the necessary power and economy. This transmission has 1many merits of simple operation, efficient, easy manufacturing, low cost, and convenient.Key words: Low-speed Truck；Transmission；Design1 前言本課題為低速載貨汽車變速器的設(shè)計(jì)，該課題來源于結(jié)合生產(chǎn)實(shí)際。研究的主要內(nèi)容是：參與汽車的總體設(shè)計(jì)；變速器結(jié)構(gòu)型式分析和主要參數(shù)的確定；變速器結(jié)構(gòu)設(shè)計(jì)。本說明書以設(shè)計(jì)低速載貨汽車變速器的傳動(dòng)機(jī)構(gòu)為主線。第2 章著重介紹了在參與總體設(shè)計(jì)當(dāng)中，如何確定低速載貨汽車參數(shù)，進(jìn)而明確變速器應(yīng)滿足的條件及其所受的限制。第 3 章則重點(diǎn)介紹低速載貨汽車變速器的傳動(dòng)機(jī)構(gòu)的設(shè)計(jì)說明。在參與總體設(shè)計(jì)當(dāng)中，首先是對(duì)低速載貨汽車的產(chǎn)品技術(shù)規(guī)范和標(biāo)準(zhǔn)進(jìn)行分析，然后確定低速載貨汽車的總質(zhì)量，以此來選擇合適的發(fā)動(dòng)機(jī)。根據(jù)發(fā)動(dòng)機(jī)的功率以及汽車的總質(zhì)量確定該車的最高速度（滿足低速載貨汽車安全技術(shù)條件） 。關(guān)于變速器的設(shè)計(jì)，首先選擇合適的變速器確定其檔位數(shù)，接著對(duì)工況進(jìn)行分析，擬訂變速器的各檔位的傳動(dòng)比和中心距，然后計(jì)算出齒輪參數(shù)以選擇合適的齒輪并且對(duì)其進(jìn)行校核，接著是初選變速器軸與軸承并且完成對(duì)軸和軸承的校核，最終完成了變速器的零件圖和裝配圖的繪制。2 低速載貨汽車主要參數(shù)的確定2.1 質(zhì)量參數(shù)的確定本課題通過計(jì)算選用ma=3500kg。2.2 發(fā)動(dòng)機(jī)的選型針對(duì)本次設(shè)計(jì)任務(wù)選用達(dá)到歐排放標(biāo)準(zhǔn)的YD480柴油機(jī)。2.3 車速的確定計(jì)算出 Vmax62.3km/h,所以該車車速滿足要求。3 變速器的設(shè)計(jì)與計(jì)算3.1 設(shè)計(jì)方案的確定3.1.13.1.1 兩軸式兩軸式這種結(jié)構(gòu)適用于發(fā)動(dòng)機(jī)前置、前輪驅(qū)動(dòng)或發(fā)動(dòng)機(jī)后置、后輪驅(qū)動(dòng)的轎車和微、輕型貨車上，其特點(diǎn)是輸入軸和輸出軸平行，無中間軸。低速載貨汽車變速器的設(shè)計(jì)23.1.23.1.2 三軸式三軸式它的第一軸常嚙合齒輪與第二軸的各檔齒輪分別與中間軸的相應(yīng)齒輪相嚙合，且第一、二軸同心。適用于傳統(tǒng)的發(fā)動(dòng)機(jī)前置、后輪驅(qū)動(dòng)的布置形式。3.1.33.1.3 液力機(jī)械式液力機(jī)械式由液力變矩器和齒輪式有級(jí)變速器組成,其特點(diǎn)是傳動(dòng)比可在最大值和最小值之間的幾個(gè)間斷范圍內(nèi)作無級(jí)變化，但結(jié)構(gòu)復(fù)雜，造價(jià)高，傳動(dòng)效率低。3.1.43.1.4 確定方案確定方案由于低速載貨汽車一般是傳統(tǒng)的發(fā)動(dòng)機(jī)前置，后輪驅(qū)動(dòng)的布置形式，同時(shí)考慮到制造成本以及便于用戶維護(hù)等因素，現(xiàn)選用三軸式變速器。 3.2 零部件的結(jié)構(gòu)分析通過對(duì)齒輪型式、軸的結(jié)構(gòu)、軸承型式的分析，來確定所有零件的結(jié)構(gòu)。3.3 基本參數(shù)的確定3.3.13.3.1 變速器的檔位數(shù)和傳動(dòng)比變速器的檔位數(shù)和傳動(dòng)比選擇最低檔傳動(dòng)比時(shí)，應(yīng)根據(jù)汽車最大爬坡度、驅(qū)動(dòng)車輪與路面的附著力、汽車的最低穩(wěn)定車速以及主減速比和驅(qū)動(dòng)車輪的滾動(dòng)半徑等來綜合考慮、確定。它可以根據(jù)汽車最大爬坡度計(jì)算，也可以根據(jù)驅(qū)動(dòng)車輪與路面的附著條件計(jì)算。3.3.23.3.2 中心距中心距商用車變速器的中心距約在 80170mm 范圍內(nèi)變化,初選 A=100mm。3.3.33.3.3 變速器的軸向尺寸變速器的軸向尺寸初選軸向尺寸:（2.42.8）A=（2.42.8）100=240280mm。3.3.43.3.4 齒輪參數(shù)齒輪參數(shù)通過計(jì)算并參照同類車型選取標(biāo)準(zhǔn)模數(shù) m=3.5，所有齒輪采用標(biāo)準(zhǔn)齒輪。3.3.53.3.5 各檔齒輪齒數(shù)的分配各檔齒輪齒數(shù)的分配首先確定檔齒輪的齒數(shù)，然后修正中心距 A=（3.560）/2=105mm，接著確定常嚙合傳動(dòng)齒輪副的齒數(shù)，以及其他檔位的齒輪齒數(shù)，最后確定倒檔齒輪副的齒數(shù)。3.4 齒輪的設(shè)計(jì)計(jì)算3.4.13.4.1 幾何尺寸計(jì)算幾何尺寸計(jì)算分別根據(jù)齒數(shù)和模數(shù)計(jì)算出尺寸。3.4.23.4.2 齒輪的材料及熱處理齒輪的材料及熱處理本課題變速器齒輪選用材料是 20CrMnTi，采用滲碳處理。33.4.33.4.3 齒輪的彎曲強(qiáng)度齒輪的彎曲強(qiáng)度因?yàn)樵撟兯倨魉械凝X輪采用同一種材料，所以當(dāng)校核時(shí)只要校核受力最大和危險(xiǎn)的檔位齒輪。分別計(jì)算出檔、倒檔齒輪的彎曲強(qiáng)度且都滿足要求。3.4.43.4.4 齒輪的接觸強(qiáng)度齒輪的接觸強(qiáng)度常嚙合齒輪副，檔、檔、檔、倒檔的齒輪都滿足強(qiáng)度要求。3.5 軸的設(shè)計(jì)與軸承的選擇3.5.13.5.1 軸軸的設(shè)計(jì)的設(shè)計(jì)軸的尺寸可按關(guān)系式初選。首先校核第二軸在各檔位下的強(qiáng)度與剛度，然后校核中間軸在各檔位下的強(qiáng)度與剛度，最后校核倒檔軸的強(qiáng)度與剛度。3.5.23.5.2 軸承的選擇軸承的選擇第一軸后軸承為 6209 軸承,第二軸后軸承為 6307 軸承。第二軸前端選用無套圈長(zhǎng)圓柱滾子軸承,型號(hào)為:KNL20.61233.32535；在中間軸上與中間軸齒輪配合的軸承，也選用該種軸承，型號(hào)為：KNL25.441.20860.4。4 結(jié)論本課題是針對(duì)低速載貨汽車而設(shè)計(jì)的變速器，基于經(jīng)濟(jì)實(shí)用的考慮，變速器采用手動(dòng)機(jī)械變速，三軸式傳動(dòng)機(jī)構(gòu)布置方案，有四個(gè)前進(jìn)檔和一個(gè)倒檔。典型輕型貨車 NJ130 系列的變速器齒輪大多采用非標(biāo)準(zhǔn)齒輪，本次設(shè)計(jì)的變速器齒輪等零部件貫徹了國(guó)家或行業(yè)的最新標(biāo)準(zhǔn)，具有較好的加工和使用性能，結(jié)構(gòu)緊湊、使用維修方便，并可附裝取力機(jī)構(gòu)供用戶的特殊需要。隨著城鄉(xiāng)路況的好轉(zhuǎn)，以及人們對(duì)乘車舒適性的要求越來越高，日后可以考慮采用常嚙合斜齒輪傳動(dòng)，同步器換檔的變速器，而且可以增加一個(gè)超速檔，這樣可以使汽車的動(dòng)力性和經(jīng)濟(jì)性有更大地提高。主要參考文獻(xiàn)主要參考文獻(xiàn)1 GB7258-2004，機(jī)動(dòng)車運(yùn)行安全技術(shù)條件S.2 GB18320-2001，農(nóng)用運(yùn)輸車安全技術(shù)條件S.3 王望予.汽車設(shè)計(jì)M.北京：機(jī)械工業(yè)出版社，2000.4 劉惟信.汽車設(shè)計(jì)M.北京：清華大學(xué)出版社,2001.5 陳家瑞.汽車構(gòu)造.（下冊(cè)）M.北京：機(jī)械工業(yè)出版社，2005. 機(jī)械設(shè)計(jì)制造及其自動(dòng)化專業(yè)外文翻譯 How Automatic Transmissions Work by Karim Nice Introduction to How Automatic Transmissions Work If you have ever driven a car with an automatic transmission, then you know that there are two big differences between an automatic transmission and a manual transmission: There is no clutch pedal in an automatic transmission car. There is no gear shift in an automatic transmission car. Once you put the transmission into drive, everything else is automatic. Both the automatic transmission (plus its torque converter) and a manual transmission (with its clutch) accomplish exactly the same thing, but they do it in totally different ways. It turns out that the way an automatic transmission does it is absolutely amazing! Automatic Transmission Image Gallery In this article, we'll work our way through an automatic transmission. We'll start with the key to the whole system: planetary gearsets. Then we'll see how the transmission is put together, learn how the controls work and discuss some of the intricacies involved in controlling a transmission. Just like that of a manual transmission, the automatic transmission's primary job is to allow the engine to operate in its narrow range of speeds while providing a wide range of output speeds. Photo courtesy DaimlerChrysler Mercedes-Benz CLK, automatic transmission, cut-away model Without a transmission, cars would be limited to one gear ratio, and that ratio would have to be selected to allow the car to travel at the desired top speed. If you wanted a top speed of 80 mph, then the gear ratio would be similar to third gear in most manual transmission cars. You've probably never tried driving a manual transmission car using only third gear. If you did, you'd quickly find out that you had almost no acceleration when starting out, and at high speeds, the engine would be screaming along near the red-line. A car like this would wear out very quickly and would be nearly undriveable. So the transmission uses gears to make more effective use of the engine's torque, and to keep the engine operating at an appropriate speed. The key difference between a manual and an automatic transmission is that the manual transmission locks and unlocks different sets of gears to the output shaft to achieve the various gear ratios, while in an automatic transmission, the same set of gears produces all of the different gear ratios. The planetary gearset is the device that makes this possible in an automatic transmission. Let's take a look at how the planetary gearset works. Planetary Gearsets & Gear Ratios When you take apart and look inside an automatic transmission, you find a huge · An ingenious planetary gearset · A set of bands to lock parts of a gearset · A set of three wet-plate clutches to lock other parts of the gearset · An incredibly odd hydraulic system that controls the clutches and bands · A large gear pump to move transmission fluid around The center of attention is the planetary gearset. About the size of a cantaloupe, this one part creates all of the different gear ratios that the transmission can produce. Everything else in the transmission is there to help the planetary gearset do its thing. This amazing piece of gearing has appeared on HowStuffWorks before. You may recognize it from the electric screwdriver article. An automatic transmission contains two complete planetary gearsets folded together into one component. See How Gear Ratios Work for an introduction to planetary gearsets. From left to right: the ring gear, planet carrier, and two sun gears Any planetary gearset has three main components: · The sun gear · The planet gears and the planet gears' carrier · The ring gear Each of these three components can be the input, the output or can be held stationary. Choosing which piece plays which role determines the gear ratio for the gearset. Let's take a look at a single planetary gearset. One of the planetary gearsets from our transmission has a ring gear with 72 teeth and a sun gear with 30 teeth. We can get lots of different gear ratios out of this gearset. Input Output Stationary Calculation Gear Ratio A Sun (S) Planet Carrier (C) Ring (R) 1 + R/S 3.4:1 B Planet Carrier (C) Ring (R) Sun (S) 1 / (1 + S/R) 0.71:1 C Sun (S) Ring (R) Planet Carrier (C) -R/S -2.4:1 Also, locking any two of the three components together will lock up the whole device at a 1:1 gear reduction. Notice that the first gear ratio listed above is a reduction -- the output speed is slower than the input speed. The second is an overdrive -- the output speed is faster than the input speed. The last is a reduction again, but the output direction is reversed. There are several other ratios that can be gotten out of this planetary gear set, but these are the ones that are relevant to our automatic transmission. You can try these out in the animation below: So this one set of gears can produce all of these different gear ratios without having to engage or disengage any other gears. With two of these gearsets in a row, we can get the four forward gears and one reverse gear our transmission needs. We'll put the two sets of gears together in the next section. Compound Planetary Gearset This automatic transmission uses a set of gears, called a compound planetary gearset, that looks like a single planetary gearset but actually behaves like two planetary gearsets combined. It has one ring gear that is always the output of the transmission, but it has two sun gears and two sets of planets. Let's look at some of the parts: How the gears in the transmission are put together Left to right: the ring gear, planet carrier, and two sun gears The figure below shows the planets in the planet carrier. Notice how the planet on the right sits lower than the planet on the left. The planet on the right does not engage the ring gear -- it engages the other planet. Only the planet on the left engages the ring gear. Planet carrier: Note the two sets of planets. Next you can see the inside of the planet carrier. The shorter gears are engaged only by the smaller sun gear. The longer planets are engaged by the bigger sun gear and by the smaller planets. Inside the planet carrier: Note the two sets of planets. Automatic Transmission Gears First Gear In first gear, the smaller sun gear is driven clockwise by the turbine in the torque converter. The planet carrier tries to spin counterclockwise, but is held still by the one-way clutch (which only allows rotation in the clockwise direction) and the ring gear turns the output. The small gear has 30 teeth and the ring gear has 72, so the gear ratio is: Ratio = -R/S = - 72/30 = -2.4:1 So the rotation is negative 2.4:1, which means that the output direction would be opposite the input direction. But the output direction is really the same as the input direction -- this is where the trick with the two sets of planets comes in. The first set of planets engages the second set, and the second set turns the ring gear; this combination reverses the direction. You can see that this would also cause the bigger sun gear to spin; but because that clutch is released, the bigger sun gear is free to spin in the opposite direction of the turbine (counterclockwise). Second Gear This transmission does something really neat in order to get the ratio needed for second gear. It acts like two planetary gearsets connected to each other with a common planet carrier. The first stage of the planet carrier actually uses the larger sun gear as the ring gear. So the first stage consists of the sun (the smaller sun gear), the planet carrier, and the ring (the larger sun gear). The input is the small sun gear; the ring gear (large sun gear) is held stationary by the band, and the output is the planet carrier. For this stage, with the sun as input, planet carrier as output, and the ring gear fixed, the formula is: 1 + R/S = 1 + 36/30 = 2.2:1 The planet carrier turns 2.2 times for each rotation of the small sun gear. At the second stage, the planet carrier acts as the input for the second planetary gear set, the larger sun gear (which is held stationary) acts as the sun, and the ring gear acts as the output, so the gear ratio is: 1 / (1 + S/R) = 1 / (1 + 36/72) = 0.67:1 To get the overall reduction for second gear, we multiply the first stage by the second, 2.2 x 0.67, to get a 1.47:1 reduction. This may sound wacky, but it works. Third Gear Most automatic transmissions have a 1:1 ratio in third gear. You'll remember from the previous section that all we have to do to get a 1:1 output is lock together any two of the three parts of the planetary gear. With the arrangement in this gearset it is even easier -- all we have to do is engage the clutches that lock each of the sun gears to the turbine. If both sun gears turn in the same direction, the planet gears lockup because they can only spin in opposite directions. This locks the ring gear to the planets and causes everything to spin as a unit, producing a 1:1 ratio. Overdrive By definition, an overdrive has a faster output speed than input speed. It's a speed increase -- the opposite of a reduction. In this transmission, engaging the overdrive accomplishes two things at once. If you read How Torque Converters Work, you learned about lockup torque converters. In order to improve efficiency, some cars have a mechanism that locks up the torque converter so that the output of the engine goes straight to the transmission. In this transmission, when overdrive is engaged, a shaft that is attached to the housing of the torque converter (which is bolted to the flywheel of the engine) is connected by clutch to the planet carrier. The small sun gear freewheels, and the larger sun gear is held by the overdrive band. Nothing is connected to the turbine; the only input comes from the converter housing. Let's go back to our chart again, this time with the planet carrier for input, the sun gear fixed and the ring gear for output. Ratio = 1 / (1 + S/R) = 1 / ( 1 + 36/72) = 0.67:1 So the output spins once for every two-thirds of a rotation of the engine. If the engine is turning at 2000 rotations per minute (RPM), the output speed is 3000 RPM. This allows cars to drive at freeway speed while the engine speed stays nice and slow. Reverse Reverse is very similar to first gear, except that instead of the small sun gear being driven by the torque converter turbine, the bigger sun gear is driven, and the small one freewheels in the opposite direction. The planet carrier is held by the reverse band to the housing. So, according to our equations from the last page, we have: Ratio = -R/S = 72/36 = 2.0:1 So the ratio in reverse is a little less than first gear in this transmission. Gear Ratios This transmission has four forward gears and one reverse gear. Let's summarize the gear ratios, inputs and outputs: Gear Input Output Fixed Gear Ratio 1st 30-tooth sun 72-tooth ring Planet carrier 2.4:1 2nd 30-tooth sun Planet carrier 36-tooth ring 2.2:1 Planet carrier 72-tooth ring 36-tooth sun 0.67:1 Total 2nd 1.47:1 3rd 30- and 36-tooth suns 72-tooth ring 1.0:1 OD Planet carrier 72-tooth ring 36-tooth sun 0.67:1 Reverse 36-tooth sun 72-tooth ring Planet carrier -2.0:1 After reading these sections, you are probably wondering how the different inputs get connected and disconnected. This is done by a series of clutches and bands inside the transmission. In the next section, we'll see how these work. Clutches and Bands in an Automatic Transmission In the last section, we discussed how each of the gear ratios is created by the transmission. For instance, when we discussed overdrive, we said: In this transmission, when overdrive is engaged, a shaft that is attached to the housing of the torque converter (which is bolted to the flywheel of the engine) is connected by clutch to the planet carrier. The small sun gear freewheels, and the larger sun gear is held by the overdrive band. Nothing is connected to the turbine; the only input comes from the converter housing. To get the transmission into overdrive, lots of things have to be connected and disconnected by clutches and bands. The planet carrier gets connected to the torque converter housing by a clutch. The small sun gets disconnected from the turbine by a clutch so that it can freewheel. The big sun gear is held to the housing by a band so that it could not rotate. Each gear shift triggers a series of events like these, with different clutches and bands engaging and disengaging. Let's take a look at a band. Bands In this transmission there are two bands. The bands in a transmission are, literally, steel bands that wrap around sections of the gear train and connect to the housing. They are actuated by hydraulic cylinders inside the case of the transmission. One of the bands In the figure above, you can see one of the bands in the housing of the transmission. The gear train is removed. The metal rod is connected to the piston, which actuates the band. The pistons that actuate the bands are visible here. Above you can see the two pistons that actuate the bands. Hydraulic pressure, routed into the cylinder by a set of valves, causes the pistons to push on the bands, locking that part of the gear train to the housing. The clutches in the transmission are a little more complex. In this transmission there are four clutches. Each clutch is actuated by pressurized hydraulic fluid that enters a piston inside the clutch. Springs make sure that the clutch releases when the pressure is reduced. Below you can see the piston and the clutch drum. Notice the rubber seal on the piston -- this is one of the components that is replaced when your transmission gets rebuilt. One of the clutches in a transmission The next figure shows the alternating layers of clutch friction material and steel plates. The friction material is splined on the inside, where it locks to one of the gears. The steel plate is splined on the outside, where it locks to the clutch housing. These clutch plates are also replaced when the transmission is rebuilt. The clutch plates The pressure for the clutches is fed through passageways in the shafts. The hydraulic system controls which clutches and bands are energized at any given moment. FROM: http://auto.howstuffworks.com/automatic-transmission.htm 24 自動(dòng)變速器的工作原理 耐斯·卡瑞姆 介紹自動(dòng)變速器的工作原理 如果你駕駛過帶有自動(dòng)變速器的汽車，那么你一定知道手動(dòng)變速器與自動(dòng)變速器之間存在兩個(gè)很大的區(qū)別： · 自動(dòng)變速器中沒有離合器踏板 · 自動(dòng)變速器中沒有換檔手柄，一旦讓變速器傳遞動(dòng)力，那么接下來的一切都是自動(dòng)完成的了。 雖然自動(dòng)變速器（包括液力變矩器）與手動(dòng)變速器（包括離合器）完成的功能是相同的，但它們卻是以完全不同的方式來實(shí)現(xiàn)的。最終證實(shí)，自動(dòng)變速器的工作方式令人驚異。 自動(dòng)變速器概圖 本文是通過一個(gè)具體的自動(dòng)變速器來闡述其中的原理，我們從整個(gè)系統(tǒng)的關(guān)鍵——行星齒輪系入手，然后我們將看到自動(dòng)變速器是如何組裝在一起的，學(xué)習(xí)控制裝置是如何工作的，討論在自動(dòng)變速器控制方面的一些復(fù)雜的關(guān)系。 自動(dòng)變速器和手動(dòng)變速器一樣，主要功能就是允許發(fā)動(dòng)機(jī)工作在小范圍變速的速度內(nèi)，變速器卻能夠輸出較大變速范圍的速度。 Mercedes-奔馳 CLK, 自動(dòng)變速器,剖面立體圖 如果沒有變速器，汽車將被限制在一種傳動(dòng)比，并且那個(gè)傳動(dòng)必須被選擇作為汽車的最高期望速度。 如果您想要以80英里/小時(shí)的最高速度行駛，則傳動(dòng)比類似于手動(dòng)變速器汽車的第三檔。 您大概從未嘗試僅使用第三檔駕駛一輛手動(dòng)變速的汽車。 如果您嘗試過，您馬上會(huì)發(fā)現(xiàn)啟動(dòng)時(shí)幾乎沒有加速過程，而是直接以很高的速度啟動(dòng)，引擎是工作在警戒線附近的。這樣汽車很快就會(huì)損害，而且?guī)缀鯚o法駕駛。 因此變速器是利用齒輪來更有效地利用發(fā)動(dòng)的扭矩的，并且使得發(fā)動(dòng)機(jī)工作在適當(dāng)?shù)乃俣取? 手動(dòng)和自動(dòng)變速器之間的關(guān)鍵性區(qū)別在于：手動(dòng)變速器采用鎖止或打開不同的齒輪，從而使輸出軸獲得不同傳動(dòng)比，而在自動(dòng)變速器中，同樣是這些齒輪，但是能得到一定范圍內(nèi)所有的不同的傳動(dòng)比。而行星齒輪系是使此成為可能的裝置。 讓我們來看一下行星齒輪系是如何工作的。 行星齒輪系和齒輪傳動(dòng)比 當(dāng)您拆散自動(dòng)變速器往里面觀察，可以發(fā)現(xiàn)，在一個(gè)相對(duì)狹小的空間里布滿了很多零件。在這些零件中有： ? 一個(gè)精巧的行星齒輪系 ? 一套鎖止齒輪的鋼帶 ? 三個(gè)鎖住另外一些齒輪的濕式片式離合器 ? 控制離合器和鋼帶的復(fù)雜液壓系統(tǒng) ? 為變速器提供液壓的齒輪泵 關(guān)注的重點(diǎn)是行星齒輪系。 變速器所產(chǎn)生的所有不同的傳動(dòng)比決定于齒輪系尺寸的大小。變速器里其他的零部件是協(xié)助行星輪系產(chǎn)生不同傳動(dòng)比的。這套裝置曾經(jīng)出現(xiàn)在《材料的工作方式》中。 您可以從《電螺絲刀》中找到。 一個(gè)自動(dòng)變速器中包含有由兩套行星齒輪系組合在一起而成的一個(gè)部件。其介紹可以參見《齒輪系工作方式》。 從左到右：內(nèi)齒圈，行星架，和兩個(gè)太陽(yáng)輪 行星齒輪系有三個(gè)主要的組成部分： ? 太陽(yáng)輪 ? 行星輪和行星架 ? 內(nèi)齒圈 這三個(gè)組成中的任何一組成都可以作為輸入或輸出，或者被固定。哪些組成充當(dāng)何種角色取決于行星齒輪系的速度比。下面的動(dòng)畫可以顯示出其中的關(guān)系。 這是變速器中其中的一個(gè)行星齒輪系，內(nèi)齒圈齒數(shù)為72，太陽(yáng)輪齒數(shù)為30。我們可以從中的到很多不同的速比。 輸入 輸出 固定 計(jì)算 齒輪速比 A 太陽(yáng)輪(S) 行星架(C) 內(nèi)齒圈(R) 1 + R/S 3.4:1 b 行星架(C) 內(nèi)齒圈(R) 太陽(yáng)輪(S) 1/(1 + S/R) 0.71:1 C 太陽(yáng)輪(S) 內(nèi)齒圈(R) 行星架(C) - R/S -2.4:1 并且，鎖住三個(gè)組成中的任何兩個(gè)組成將鎖止整個(gè)個(gè)行星系，而此時(shí)速比為1：1。從表中可以看出，第一個(gè)中方案的速比為減速——輸出速度小于輸入。第二種方案為加速——輸出速度高于輸入。最后一種方案也是減速，但輸出速度的方向相反。這個(gè)行星齒輪系還可以得到其他很多的速比，而剛才的這些速比僅和我們的自動(dòng)變速器有關(guān)。 因此這一套行星齒輪系可以產(chǎn)生所有需要的不同的齒輪傳動(dòng)比，卻不需要接合或不接合其他齒輪。把兩套行星齒輪系置于一行，我們可以得到四個(gè)前進(jìn)檔和一個(gè)后退檔。下一部分內(nèi)容我們將這兩個(gè)齒輪系組裝在一起。 復(fù)合行星齒輪系 自動(dòng)變速器中使用了一系列的行星齒輪系，我們稱之為復(fù)合行星齒輪系，看起來好像只有一個(gè)簡(jiǎn)單的行星齒輪系，實(shí)際上卻實(shí)現(xiàn)這兩套齒輪系的功能。其中包含一個(gè)總是作為輸出的內(nèi)齒圈、兩個(gè)太陽(yáng)和兩套行星裝置。 讓我們看其中的一些零件： 變速器中的齒輪的組裝 從左到右：內(nèi)齒圈，行星架，和兩個(gè)太陽(yáng)輪 下圖中，行星輪裝在行星架上，可以看到，右邊的行星輪低于左邊的行星輪。右邊的行星輪不與內(nèi)齒圈嚙合——它和另一個(gè)行星輪嚙合。而只有左邊的行星輪與內(nèi)齒圈嚙合。 行星架：兩個(gè)行星輪 在下個(gè)圖中，您可看到在行星架的內(nèi)部，短行星輪與小太陽(yáng)輪嚙合，長(zhǎng)行星輪同時(shí)與大太陽(yáng)輪和小太陽(yáng)輪嚙合。 行星架內(nèi)部：兩個(gè)行星輪 自動(dòng)變速檔位 第一檔 在一檔，小太陽(yáng)輪在變矩器的渦輪驅(qū)動(dòng)下順時(shí)針旋轉(zhuǎn)。行星架將自動(dòng)做逆時(shí)針轉(zhuǎn)動(dòng)，但是被離合器阻止了（離合器只允許單向旋轉(zhuǎn)），從而內(nèi)齒圈變成了輸出。小太陽(yáng)輪有30齒，內(nèi)齒圈72齒，則速比為： Ratio = -R/S = - 72/30 = -2.4:1 因此旋轉(zhuǎn)速率為負(fù)的2.4:1，這意味著輸出方向同輸入的方向是相反的。但事實(shí)上，輸出方向是與輸入方向相同的，這就是要引入兩套行星齒輪系的原因。第一套與第二套嚙合，而第二套輸出至內(nèi)齒圈，這樣的組合把方向轉(zhuǎn)回原先輸入的方向。這樣還是使得大太陽(yáng)輪自轉(zhuǎn)，而這時(shí)的離合器是不作用的，大太陽(yáng)輪以同渦輪相反的方向（逆時(shí)針）自轉(zhuǎn)。 第二檔 變速器做一些單獨(dú)的事情來獲得二檔所需的傳動(dòng)比。它像相互連接的兩套行星輪和共同的行星架相連接。 行星架的第一級(jí)事實(shí)上是把大太陽(yáng)輪用作內(nèi)齒圈。所以第一級(jí)包括太陽(yáng)輪（小太陽(yáng)輪）、行星架和“內(nèi)齒圈”（大太陽(yáng)輪）。輸入是小太陽(yáng)輪，內(nèi)齒圈(大太陽(yáng)輪)由鋼帶保持靜止，輸出是行星架。對(duì)于一級(jí)，太陽(yáng)輪作為輸入，行星架作為輸出，而內(nèi)齒圈固定，其公式為： 1 + R/S = 1 + 36/30 = 2.2:1 小太陽(yáng)輪旋轉(zhuǎn)一圈，行星架則轉(zhuǎn)過2.2圈。在第二級(jí)，行星架作為第二套行星齒輪系的輸入，大太陽(yáng)輪（被固定）作為太陽(yáng)輪，而內(nèi)齒圈則作為輸出，其齒輪速比為： 1 / (1 + S/R) = 1 / (1 + 36/72) = 0.67:1 要得到二檔的減速比，我們把第一級(jí)減速比和第二級(jí)減速比相乘， 2.2 x 0.67，得到1.47:1。 這也許聽起來有些怪，但卻是這么運(yùn)作的。 第三檔 絕大多數(shù)的自動(dòng)變速器在第三檔是1：1的速比。您還記得前面我們已經(jīng)得到速比為1：1的方法——三個(gè)組成中鎖住任何兩個(gè)組成。這樣的裝置實(shí)現(xiàn)就比較容易——我們所要做的就是接合離合器來鎖住太陽(yáng)輪中的一個(gè)。 如果兩個(gè)太陽(yáng)輪以同一方向旋轉(zhuǎn)，行星輪則被鎖定，因?yàn)樗鼈兎聪蛐D(zhuǎn)。內(nèi)齒圈和行星輪固定使得它們作為一個(gè)整體旋轉(zhuǎn)，從而產(chǎn)生1：1的速比。 加速檔 根據(jù)定義，輸出的速度要高于輸入的速度。它是速度的增加——減速的對(duì)立面。在變速器中，加速時(shí)在同一時(shí)刻完成兩件事情。如果您看過《變矩器是如何工作的》，就知道變矩器的鎖止的情況。為了提高效率，一些汽車用機(jī)械方式鎖住變矩器，使得發(fā)動(dòng)機(jī)的扭矩直接輸出到變速器。 變速器中，當(dāng)加速時(shí)，聯(lián)接到變矩器的外殼（用螺栓連接到發(fā)動(dòng)機(jī)的飛輪）的軸通過離合器的接合連接到行星架，小太陽(yáng)輪和大太陽(yáng)輪與加速鋼帶同步，渦輪不接其他東西，而變矩器的外殼作為輸出。我們回顧一下，此時(shí)行星架作為輸入，太陽(yáng)輪固定，而內(nèi)齒圈作為輸出。 Ratio = 1 / (1 + S/R) = 1 / ( 1 + 36/72) = 0.67:1 可得到，發(fā)動(dòng)機(jī)輸入旋轉(zhuǎn)速度為輸出的三分之二。例如，如果發(fā)動(dòng)機(jī)轉(zhuǎn)速為每分鐘2000轉(zhuǎn)，輸出轉(zhuǎn)速就為3000轉(zhuǎn)每分鐘。這就允許發(fā)動(dòng)機(jī)以相對(duì)合適的速度運(yùn)轉(zhuǎn)，汽車也能夠在高速公路上行駛。 倒檔 倒檔和一檔非常類似，區(qū)別在于，不是小太陽(yáng)輪被驅(qū)動(dòng)，而是大太陽(yáng)輪被驅(qū)動(dòng)，而小行星輪以相反方向旋轉(zhuǎn)。行星架與變矩器外殼同步，則根據(jù)上述的公式可以得到： Ratio = -R/S = 72/36 = 2.0:1 可見，變速器倒檔的傳動(dòng)比比一檔稍小一些。 齒輪傳動(dòng)比 此變速器有四個(gè)前進(jìn)檔和一個(gè)倒檔，讓我們用傳動(dòng)比、輸入和輸出總結(jié)一下： 檔 位 輸 入 輸 出 固 定 齒輪傳動(dòng)比 第1 檔 30齒太陽(yáng)輪 72齒內(nèi)齒圈 行星架 2.4:1 第2檔 30齒太陽(yáng)輪 行星架 36齒內(nèi)齒圈 2.2:1 行星架 72齒內(nèi)齒圈 30齒太陽(yáng)輪 0.67:1 兩級(jí)總比 1.47:1 第3 檔 30和36齒太陽(yáng) 72齒內(nèi)齒圈 1.0:1 加速檔 行星架 72齒內(nèi)齒圈 36齒太陽(yáng) 0.67:1 倒 檔 30齒太陽(yáng)輪 72齒內(nèi)齒圈 行星架 -2.0:1 在讀完這部分之后，您大概想知道不同的輸入是怎么接合與斷開的。這是由變速器中的離合器和鋼帶完成的。在下一部分中，我們將看到它們是如何工作的。 變速器中的離合器和鋼帶 在上一部分，我們討論了變速器是如何得到不同檔位的傳動(dòng)比的。例如，討論加速檔是，我們說： 變速器中，當(dāng)加速時(shí)，聯(lián)接到變矩器的外殼（用螺栓連接到發(fā)動(dòng)機(jī)的飛輪）的軸通過離合器的接合連接到行星架，小太陽(yáng)輪和大太陽(yáng)輪與加速鋼帶同步，渦輪不接其他東西，而變矩器的外殼作為輸出。 要讓變速器工作在加速檔，很多零部件要通過離合器和鋼帶連接或斷開。行星架通過離合器與變矩器外殼連接。小太陽(yáng)輪通過離合器斷開與渦輪連接，使其空轉(zhuǎn)。大太陽(yáng)輪利用鋼帶與外殼同步，使其無法旋轉(zhuǎn)。像這樣通過離合器與鋼帶的接合或不接合，每個(gè)齒輪運(yùn)動(dòng)都會(huì)觸發(fā)一系列的事件。讓我們看一下鋼帶。 鋼帶 變速器中有兩條鋼帶，這兩條鋼帶事實(shí)上是包貼在齒輪組切面周圍的，并且連接到外殼，由變速器的液壓缸推動(dòng)執(zhí)行的。 其中的鋼帶 在上圖中，您可以看到在變速器外殼上其中的一條鋼帶。此時(shí)齒輪都已經(jīng)被移走了，金屬推桿與活塞相連，用來推動(dòng)鋼帶。 活塞推動(dòng)鋼帶 上圖可看到驅(qū)動(dòng)鋼帶的兩個(gè)活塞。油壓通過液壓閥控制進(jìn)入液壓缸，驅(qū)動(dòng)活塞推動(dòng)鋼帶，從而使得齒輪系中的某個(gè)組成與外殼鎖止。 變速器中的離合器共有四個(gè)，而且相對(duì)來說要復(fù)雜一些。被壓縮的液壓油進(jìn)入離合器內(nèi)部的活塞，從而驅(qū)動(dòng)離合器。當(dāng)油壓降低時(shí)，彈簧確保離合器分離后回復(fù)原位。下圖所示為活塞和離合器從動(dòng)鼓，還要注意到活塞上的密封橡膠圈，當(dāng)變速器被重新修理裝配時(shí)，要求更換這個(gè)橡膠圈。 變速器中的一個(gè)離合器 下圖所示的是離合器中相互交替的摩擦片與金屬片。摩擦片內(nèi)側(cè)由花鍵聯(lián)接，與輪系的其中一個(gè)組成鎖止。金屬片外側(cè)用花鍵與離合器外殼固接。同樣，變速器被修理時(shí)，這些離合器片要被更換。 離合器片 離合器的油壓是通過經(jīng)由軸內(nèi)通道來供應(yīng)的。在任一時(shí)刻，離合器和鋼帶的運(yùn)動(dòng)都是有液壓系統(tǒng)控制的。 注：本文來源: http://auto.howstuffworks.com/automatic-transmission.htm