摩擦式無級變速器結(jié)構(gòu)設(shè)計-裝配圖新版本【含9張CAD圖紙+文檔全套】

喜歡就充值下載吧。資源目錄里展示的文件全都有，請放心下載，有疑問咨詢QQ:414951605或者1304139763 = 喜歡就充值下載吧。資源目錄里展示的文件全都有，請放心下載，有疑問咨詢QQ:414951605或者1304139763 = 附錄： 文獻(xiàn)翻譯部分中文翻譯1.摘要 自1996年起,當(dāng)?shù)谝粋€應(yīng)用CVT變速技術(shù)的農(nóng)業(yè)拖拉機(jī)展出后，該類型的變速技術(shù)就一直在增加。所有公司都將該變速技術(shù)應(yīng)用在它們的產(chǎn)品系列。然而,很少有技術(shù)文件能解釋其基本的操作。所有公司奧費爾他們在他們的產(chǎn)品范圍。然而，很少有技術(shù)文件，說明其運作的基本知識。這份報告表明，所有類型的CVT變速器：非電分體式和權(quán)力分割的，以及3個農(nóng)用拖拉機(jī)，液壓機(jī)械功率分裂傳輸（3主動軸，行星耦合輸入;積極利用3種軸，行星和4個輸出耦合主動軸）。報告還描述了一個CVT變速箱，采用3軸功率活躍，分裂系統(tǒng)以及它們之間的基本關(guān)系式的設(shè)計參數(shù)。 2010年官方版權(quán)由Elsevier出版有限公司對ISTVS代表。保留所有權(quán)利。關(guān)鍵詞：無級變速器，變速箱，液壓機(jī)械功率分流傳動，液壓無級變速器，牽引傳動 2. 介紹 自誕生之日起,在農(nóng)業(yè)變速拖拉機(jī)研制就與農(nóng)業(yè)需求相結(jié)合,用發(fā)動機(jī)和變速箱來改良拖拉機(jī)的性能,使得有更多的踩變速器齒輪。由于電腦技術(shù)的應(yīng)用到拖拉機(jī)的生產(chǎn)，使得j機(jī)械自動化管理這兩個因素變成可能。然而,讓拖拉機(jī)憑借著高數(shù)量的齒輪轉(zhuǎn)移到另一個地方液壓制動管傳輸是必要的。在這種情況下，CVT技術(shù)在農(nóng)業(yè)拖拉機(jī)上的應(yīng)用為完整的管理和對駕駛戰(zhàn)略鋪平了道路,并提高了勞動生產(chǎn)率和舒適度。CVT 在運輸業(yè)從1996年被應(yīng)用于農(nóng)業(yè)拖拉機(jī)開始。貢獻(xiàn)是多方面的,尤其是它那令人驚嘆的創(chuàng)意，這與它作為一輛汽車的價值無關(guān)。它和其他的技術(shù)的不同在于它更容易使用。芬特的蔡司是因為它的創(chuàng)意令人驚訝，它是不相關(guān)的汽車，以它的等效。它分為兩方面的力量和稍后再加入。它是創(chuàng)新的，但更容易使用，而不是理解。然后，斯太爾病例的S - Matic的來到了一系列生產(chǎn)，這也是一個權(quán)力分割，但是非常不同。另一方面，在德國，克拉斯有車，有一個類似的傳輸Xerion：人機(jī)界面，后來導(dǎo)致航模- II的。一類同時它取代了ZFECCOM無級變速器。然后，約翰迪爾被納入無級變速家庭有兩個傳輸AUTOPOWR這是在外面，相對于管理和駕駛策略相同，但里面的不同。后來，道依茨介紹了Agrotron臺視和新荷蘭引進(jìn)了TM系列傳輸連續(xù)生產(chǎn)能力達(dá)8000噸。最近，梅西弗格森已經(jīng)開發(fā)敦南電視傳輸和麥考密克已開發(fā)VTX。其結(jié)構(gòu)是在德國提出年鑒農(nóng)業(yè)工程。 這些類型的傳輸一直深受農(nóng)民的歡迎，因其明顯的優(yōu)勢,例如它們舒適，易于操作,并滿足了最多樣化的需求。然而，因為缺乏系統(tǒng)的理論研究，這種傳輸技術(shù)的推廣受到了限制。2. CVT 傳輸?shù)念愋虲VT 傳輸?shù)闹饕卣魇菬o段式的速度變化。 一個允許無限的連續(xù)的可變單位齒輪比，一定被允許的。有 CVT 傳輸系統(tǒng)的不同類型哪一個能依照一些標(biāo)準(zhǔn)被分類：1） 力量流程。2） variator 的類型。3） 它的成份的性質(zhì)。分類的第一個標(biāo)準(zhǔn)是動力流程 。在非開式類型中，只有一條路徑為這個使流過有動力。 這些 CVT 被提出當(dāng)做 橋?qū)?式的. 在相反者身上，在分散的類型中，動力在兩條路徑中被分離然后再合并。 此外，有混合流程 CVT，已經(jīng)兩動力流程讓它操作的路徑 （剎車和抓緊）在不同的模態(tài)中，像是分散的或非開式的，或在一些其他式樣 .環(huán)形的運輸 的兩類型存在，機(jī)械的而且水力的。在機(jī)械工類型里面，有帶子、鏈和滾筒被環(huán)形的傳輸. 這些被用于CVT 傳輸在汽車、摩托車和牽引者中發(fā)現(xiàn)原型。 關(guān)于水力的 環(huán)形的運輸 ，有另外的兩類型： 流體靜力學(xué)傳輸和轉(zhuǎn)力矩轉(zhuǎn)換器。依照分類的第三個標(biāo)準(zhǔn)，自然成份在 CVT 傳輸中包含，有一些不同的種類。 成份罐子要所有機(jī)械的，所有的水力的，或組合機(jī)械、水力的元素 . 在全部機(jī)械 里面類型，分散的而且非開式存在。 劈開打字，流體靜力學(xué)和水動力學(xué)傳輸，然而，不在全部里面在場水力的傳輸。 混合的機(jī)械水力的傳輸能被分離或在系列中結(jié)構(gòu)。3.動力開式的 CVT 傳輸動力開式的傳輸把力量分為二路徑，一用固定的傳輸比（這機(jī)械的路徑）和另外的哪一個包括變數(shù)路徑.兩者都在輸出橋中再加入。CVT 效果是由路徑提供以變數(shù)路徑。有商業(yè)傳輸?shù)娜煌愋?1） 3個活躍的橋：輸入加倍行星的或總計行星的。 輸出加倍行星的或分配的人行星的。2） 4個活躍的橋：橋類型行星的。 活躍橋 的定義提及被連接的那些到行星的齒輪火車 , 這真實的機(jī)械的CVT 系統(tǒng)的心。當(dāng)有 3個活躍的橋，PGT 一個機(jī)械的輸入橋 , 一或一些輸出橋 和一個漂浮的橋連接對 變數(shù)路徑.另一方面，在 4 中活躍的橋打字，也知道當(dāng)做 橋打字 , 這兩個 環(huán)形運輸橋與 PGT 一起連接。在傳輸中以 3個活躍的行星橋在那里兩個節(jié)是，一在 CVT 組件的輸入，和這在輸出的其他。兩個基本的結(jié)構(gòu)是已知的;他們之間的不同取決于這PGT 的位置。在輸入中加倍了行星的（總計行星的）, PGT 是輸出節(jié)和輸入節(jié)是聯(lián)結(jié)。在輸出方面加倍行星的（分配的人行星的）, 輸入節(jié)是 PGT 和輸出節(jié)是聯(lián)結(jié)。因為那里的每個地面區(qū)劃是操作的 3個式樣依照流經(jīng)的動力流動的 CVT .如果動力流動過路徑之一比輸入棒，動力據(jù)說變得再生。在差別中，當(dāng)動力流過每個這兩條路徑比輸入低，動力據(jù)說是非再生的。在再生的動力方案中，自從有兩條路徑，情形能出現(xiàn)：1）動力完成的固定路徑是更棒的超過這輸入動力. （機(jī)械的再生）2） 經(jīng)過可變的路徑的動力是更棒的超過這輸入動力. （可變的再生）。4.動力開式 CVT 的元素與 3 活躍的行星的橋CVT 傳輸?shù)幕驹厥?1） CVT 單位輸入橋 .旋轉(zhuǎn)率：舊式的2） CVT 單位輸出橋 .旋轉(zhuǎn)率：沒有3） 聯(lián)結(jié)或聯(lián)接：2 橋的節(jié)：一對可變的路徑連接的 。一對機(jī)械的路徑連接的 。4）行星的齒輪火車 （PGT）:節(jié)與，至少， 3活躍的橋：對 PGT的 機(jī)械的輸入橋.旋轉(zhuǎn)比率。PGT的 機(jī)械的輸出橋.旋轉(zhuǎn)率。 橋?qū)勺兊穆窂竭B接，呼叫漂浮的橋 .旋轉(zhuǎn)率。5） 環(huán)形運輸: （不斷可變的單位）與 2橋：2:對漂浮的橋連接（旋轉(zhuǎn)率). 橋 1:對聯(lián)結(jié)連接。（旋轉(zhuǎn)率 )6） 內(nèi)在的機(jī)械傳輸：PGT 和 環(huán)形運輸 之間的連結(jié).環(huán)形運輸 和聯(lián)結(jié) 之間的連結(jié).在機(jī)械的路徑 中的 .5.參數(shù)為動力開式的 CVT 用 3-橋行星的為了要了解 CVT 傳輸?shù)牟僮?，定義一系列參數(shù)是有用的被哪一個他們被表示的特色。出名紙包含（除其他系統(tǒng)之外） 動力分離 的完全模型系統(tǒng)用 3-橋標(biāo)準(zhǔn)的行星。作家發(fā)展在這一種基礎(chǔ)方面的他們的叁數(shù)研究，然而他們以包含的結(jié)構(gòu)這么做一另外的齒輪裝置 的比在這之間行星的和秒聯(lián)接點。基本的這擴(kuò)大構(gòu)成被 能改善適應(yīng)商業(yè)的力量劈開的系統(tǒng)藉由內(nèi)在的傳輸在行星的之間和聯(lián)接點。內(nèi)在傳輸比的定義根據(jù)以 的方法學(xué)為基礎(chǔ)的圖 2 有:1） 傳輸在 PGT 的機(jī)械路徑中的比。2） 傳輸 PGT 的漂浮元素的比。3） 傳輸在 CVT 組件中的比：PGT 橋的速度之間的比是被基本的速度相等表達(dá)當(dāng)做顯示在表現(xiàn)的圖 中,藉由參數(shù)公里,這兩條路徑的轉(zhuǎn)力矩的部份假定沒有使損失有力量。關(guān)門時間是重點在哪一個力量劈開CVT 傳輸變成純粹機(jī)械，這漂浮的橋作為固定之物體和傳輸比當(dāng)做這關(guān)門時間比。當(dāng)計算 CVT 傳輸，為了要達(dá)成，第一個步驟將分析 PGT關(guān)門時間傳輸比和價值為參數(shù)公里。一經(jīng)給定時間的比指出傳輸和漂浮的元素被知道，我們能計算傳輸使用下列的公式為 PGT 比，哪一個對傳輸?shù)乃蓄愋陀行Вǚ峙涞娜撕涂傆嬓行堑模? Rt = Rtb + Rf （1 Rtb）6.結(jié)論這項研究已被寫入與樓目標(biāo)奠定了K是一套觀念將在分類和援助下，站立式CVT變速箱，以及，以目前的1公里，一般參數(shù)計劃在以下方面為他們描繪的代表。這些參數(shù)代表了扭矩的機(jī)械和可變路徑和鎖定傳動比，可作為對這些參數(shù)的函數(shù)的分布計算。對于一般的傳動設(shè)計圖概述。設(shè)計參數(shù)都是為他們提供（尺寸和配置的特點），確定了鎖定傳動比，以及變速器的比例，這符合計算的浮動軸（一個連接，擴(kuò)展到變速器的傳動比）。鏈接的公式上述參數(shù)已經(jīng)建立起來，并在一個為培訓(xùn)目的，這是目前在耕作的拖拉機(jī)和“研究的馬德里理工大學(xué)的一批實驗室建設(shè)模式設(shè)計實施。7. 參考文獻(xiàn)1 Browning EP. Design of agricultural tractor transmission elements.In: ASAE distinguished lecture No. 4. MI (USA): St. Joseph; 1978.2 Fredriksen N. TRAXION the 2nd generation of power splittransmissions from CLAAS (long version). Transmission presentation.CLAAS Industrietechnik GmbH; 2001.3 Garc?a G. Disen?o del prototipo de una transmision CVT conramificacion de potencia mecanica-mecanica. MBA thesis. UniversidadPolitecnica de Madrid; 2005.4 Gomez M. A continuously variable power-split transmission in ahybrid electric sport utility vehicle. PhD thesis. West VirginiaUniversity; 2003.5 Hsieh L, Yan H. On the mechanical efficiency of continuouslyvariable transmissions with planetary gear trains. Int J Vehicle Des1990;11(2):17787.6 Kress JH. Variable-speed transmission combined with planetarydrive. US Patent 3251243, filed 21.05.1962, granted 17.05.1966; 1962.7 Kress JH. Hydrostatic power-splitting transmissions for wheeledvehicles. Classification and theory of operation. SAE Paper No.680549; 1968.8 Linares P. Transmisiones CVT con Ramificacion Mecanica-Hidrostatica de la Potencia. 1st ed. Madrid: ETSI Agronomos; 2003.9 Lu Z. Acceleration simulation of a vehicle with a continuouslyvariable power split transmission. PhD thesis. West Virginia University;1998.10 Mangialardi L, Mantriota G. Power flows and efficiency in infinitelyvariable transmissions. Mech Mach Theory 1999;34:97394.11 Mantriota G. Performances of a series infinitely variable transmissionwith type II power flow. Mech Mach Theory 2002;37:55578.12 Mantriota G. Performances of a series infinitely variable transmissionwith type I power flow. Mech Mach Theory 2002;37:57997.13 Renius KT. Trends in tractor design with particular reference toEurope. J Agric Eng Res 1994;57(1):322.14 Renius KT, Resch R. Continuously variable tractor transmissions. In:ASAE distinguished lecture No. 29. MI (USA): St. Joseph; 2005.15 Renius KT et al. (1996-2008); Geimer M, and Renius KT (2009).Chapter “Engines and transmissions”; 2009. German Yearbook ofAgricultural Engineering.16 Resch R. Leistimgsverzweigth Mehrbereichsfahrantriebe mit Kettenwandlern(CVTs with ranges and power split for chain variators).PhD thesis. TU Munchen; 2004 Published by Fortsehritt-BerichbzVDI, Series 14, No. 21. Du sseldorf: VDI Verlag 2005.17 Sheu K-B, Chiou S-T, Hwang W-M, Wang T-S, Yan H-S. Newautomatic hybrid transmissions for motorcycles. Proc Natl Sci CouncRoc A 1999;23(6):71627.18 Shellenberger MJC. Design consideration for variable power splithydraulic drives for industrial applications. PhD thesis. West VirginiaUniversity; 1999.19 UCDavis International CVT and Hybrid Transmission Congress.Davis (CA, USA): University of California ; 2004 accessed 01.08.07.20 Wadman B. Responder automatic transmission ready for market.Diesel Gas Turbine Progr 1973;39(6):325.Design parameters for continuously variable power-splittransmissions using planetaries with 3 active shaftsP. Linaresa,b,1, V. Me ndeza,c,*,2, H. Catala na,c,3aResearch Group “Tractors and Tillage”, Universidad Polite cnica de Madrid, SpainbDpto. Ingenier a Rural, E.T.S. Ingenieros Agro nomos, Universidad Polite cnica de Madrid, Ciudad Universitaria s/n, 28040 Madrid, SpaincDpto. Matema tica Aplicada, E.T.S. Ingenieros Agro nomos, Universidad Polite cnica de Madrid, Ciudad Universitaria s/n, 28040 Madrid, SpainReceived 6 February 2009; received in revised form 14 April 2010; accepted 19 April 2010AbstractSince 1996, when the first agricultural tractor with CVT transmission was shown, the presence of this type of transmissions has beenincreasing. All companies offer them in their products range. Nevertheless, there is little technical documentation that explains the basicsof its operation. This report shows all types of CVT transmissions: non-power-split type and power-split ones, as well as the three typesused in agricultural tractors, hydro-mechanical power-split transmissions (3 active shafts, input coupled planetary; 3 active shafts, outputcoupled planetary and 4 active shafts). The report also describes the design parameters of a type of CVT transmission, which use apower-split system with 3 active shafts as well as the fundamental relations among them.Crown Copyright ? 2010 Published by Elsevier Ltd. on behalf of ISTVS. All rights reserved.Keywords: CVT; Transmission; Hydro-mechanical power-split transmission; Hydrostatic CVT; Tractor transmission1. IntroductionSince the emergence of the power-shift transmissions inagricultural tractors, the requirement to combine theengine and transmission to increase productivity in thetractors performance, has led to stepped transmissionswith a greater number of gears. The introduction of com-puting in tractors allows the possibility of managing bothfactors automatically and simultaneously. However, witha high number of gear shifts it is necessary to place a highnumber of clutches or hydraulic brakes to govern the trans-mission. Under these circumstances, the appearance ofCVT technology in agricultural tractors, paved the wayto an integral management and to the development of driv-ing strategies, which improve productivity and comfort.CVT transmissions (with continuous variation) wereinstalled in agricultural tractors beginning in 1996. FendtsVARIO was surprising because of its originality; it was notrelated to its equivalent in an automobile. It split the powerin two ways and joined it again later on. It was innovativebut much easier to use than to understand. Then, Steyr-Cases S-MATIC arrived at a series production, whichwas also a power split, but very different. On the otherhand, in Germany, Claas has a vehicle, Xerion, with a sim-ilar transmission: HM-I, which later led to HM-II 2. Cla-as meanwhile replaced it with ZFECCOM CVT. Then,John Deere was incorporated into the CVT family withtwo transmissions AUTOPOWR which were the same onthe outside, relative to management and driving strategies,but different on the inside. Later, Deutz introduced theAgrotron TTV and New Holland introduced the TM serieswith a continuous TVT transmission. Most recently, Mas-sey Ferguson has developed Dyna-TV transmission andMcCormick has developed VTX. Their structures are0022-4898/$36.00 Crown Copyright ? 2010 Published by Elsevier Ltd. on behalf of ISTVS. All rights reserved.doi:10.1016/j.jterra.2010.04.004*Corresponding author. Tel.: +34 913 365 854; mobile: +34 618 807499; fax: +34 913 365 845.E-mail addresses: pilar.linaresupm.es (P. Linares), valeriano.mendezupm.es (V. Me ndez), h.catalanupm.es (H. Catala n).1Tel.:+34 913 365 854; mobile: +34 618 807 499; fax: +34 913 365 845.2Tel.:+34 917 308 355; mobile: +34 616 981 407.3Tel.:+34 914 293 822; mobile: +34 605 445 online at Journal of Terramechanics xxx (2010) xxxxxxJournalofTerramechanicsARTICLE IN PRESSPlease cite this article in press as: Linares P et al., Design parameters for continuously variable power-splittransmissions using planetaries with 3 active shafts, J Terramechanics (2010), doi:10.1016/j.jterra.2010.04.004presented in the German Yearbook Agricultural Engineer-ing 15.These kinds of transmissions have been well received byfarmers because of their clear advantages, such as comfort,ease of handling, and response to the most diverse require-ments. However, there is not a systematic theory of opera-tion to study them, which is a disadvantage in presentingthe transmission characteristics.NomenclatureCring gear (or clutches in Fig. 12)Caclutch aCdclutch dCVTcontinuously variable power-split trans-missionCVUcontinuously variable unitdividerplanetaryCVT power-split transmission with thePGT in the input nodeeCVT unit input shaftemmechanical input shaft to the PGTFforwardfshaft connected to the variable path(called floating shaft)gefficiencyHMThydro-mechanical transmissioni1internal transmission in CVT unit; trans-mission ratio between PGT and CVUi2internal transmission in CVT unit; trans-mission ratio between PGT and couplingiminternal transmission in CVT unit; trans-mission ratio between CVU and couplingitoverall transmission ratio engine-wheelsIttransmission ratio in the CVT Unitkftorque ratio of the floating shaft (Mf/Memin divider planetary; Mf/Momin summingplanetary)kmtorqueratioofthemechanicalpath(Mom/Memin divider planetary; Mem/Momin summing planetary)kteeth ratio in the PGT (ZC/ZP)Memtorque in mechanical input shaft to thePGTMftorque in shaft connected to the variablebranch, called floating shaftMixedtransmissiontransmissions with a shiftable combina-tion of different modes of workMomtorque in mechanical output shaft to thePGTMRmechanical regenerative power flownrotation speedNpowern1rotation rate in shaft 1 of the variator(connected to the coupling)n2rotation rate in shaft 2 of the variator(connected to the floating shaft)nC1rotation speed in ring gear number 1 (in acommercial CVT transmission)nerotation speed in CVT input shaftNeinput power in CVT unitnemrotation speed in mechanical input shaftin PGTnfrotation rate of the floating shaft (shaftconnected to the variable path)nmrotation speed in shaft between planetarygear trainNmpower in mechanical shaftnorotation speed in CVT output shaftnomrotation speed in output shaft in PGTnoutrotation speed in output shaft in Fig 12(after even clutches box)NRnon-regenerative power flowNvPower in variable shaftoCVT unit output shaftommechanical output shaft from the PGTomrotation speed of the mechanical outputshaft(s) from the PGTPsun gearPGTplanetary gear trainPSplanet carrierRreverse gearsRftransmission ratio of the floating shaftRttransmission ratio in the mechanical pathof the planetary systemRtbtransmission ratio in the lockup pointRvtransmission ratio in the CVUShaftto shaftnon-splitted CVT transmissionSummingplanetaryCVT power-split transmission with thePGT in the output nodeTTMtransmissionteachingmodel(CVTpower-split transmission with the PGTin the output node)Variatorcontinuously variable unitVRvariable regenerative power flowVUcontinuously variable unitXmtpower distribution in mechanical pathXvtpower distribution in variable pathZnumber of teethZcnumber of teeth of the ring gearZpnumber of teeth of the sun gear2P. Linares et al./Journal of Terramechanics xxx (2010) xxxxxxARTICLE IN PRESSPlease cite this article in press as: Linares P et al., Design parameters for continuously variable power-splittransmissions using planetaries with 3 active shafts, J Terramechanics (2010), doi:10.1016/j.jterra.2010.04.0042. Types of CVT transmissionsThe main feature of CVT transmissions is a steplessspeed change. A continuous variable unit that allows infi-nite gear ratios, must be incorporated.There are different types of CVT transmission systemswhich can be classified according to several criteria:? Power flow.? Type of variator.? The nature of its components.The first criterion of classification is power flow (Fig. 1).In the non-split type, there is only a single path for thepower to flow through. These CVTs are addressed as“Shaft to Shaft” 7. On the contrary, in the split type,the power is split in two paths and then rejoined. In addi-tion, there are the mixed-flow CVTs, which have two powerflow paths (brakes and clutches) which allow it to operatein different modes, such as split or non-split, or in severalother patterns (Fig. 1).Two types of variators exist, mechanical and hydraulic.Within the mechanic type, there are belt, chain and roller-based variators (toroidal transmission). These are used inthe CVT transmission found in cars, motorcycles and trac-tor prototypes. As for hydraulic variators, there areanother two types: Hydrostatic Transmission, and torqueconverters.According to the third criterion of classification, the nat-ure of the components included in the CVT transmission,there are several different categories. The components canbe all-mechanical, all-hydraulic, or a combination ofmechanical and hydraulic elements (HM). Within the all-mechanical type, both split and non-split exist. The splittype, hydrostatic and hydrodynamic transmissions, how-ever, is not present in all-hydraulic transmissions. Mixedmechanical-hydraulic transmissions can be split or in seriesconfigurations.3. Power-split CVT transmissionsPower-split transmissions divide the power into twopaths, one with fixed transmission ratio (the mechanicalpath) and another which includes the variator (the variablepath). Both rejoin in the output shaft. The CVT effect isprovided by the path with the variator.There are three different types of commercial transmis-sions (Fig. 2):? 3 active shafts:sInput coupled planetary or summing planetary.sOutput coupled planetary or divider planetary.? 4 active shafts: bridge type planetary.The definition of “active shaft” refers to those connectedto the planetary gear train (PGT), the true mechanicalheart of the CVT system. When there are 3 active shafts,the PGT has one mechanical input shaft (em), one or sev-eral output shafts (om) and a single floating shaft con-nected to the variator (f). On the other hand, in the 4active shafts type, also known as “bridge type” 18, thetwo variator shafts are connected with the PGT.In the transmissions with 3 active planetary shafts thereare two nodes, one at the input of the CVT unit, and theother one at the output. Two basic configurations areknown 7; the difference between them depends on theposition of the PGT. In the input coupled planetary (sum-ming planetary), the PGT is the output node and the inputnode is the coupling. In the output coupled planetary (divi-der planetary), the input node is the PGT and the outputnode is the coupling.For each layout there are 3 patterns of operationaccording to the flow of power through the CVT, seeFig. 3 9. If the power flowing through one of the pathsis greater than the input, the power is said to be regenera-tive. In contrast, when the power flow through each of thetwo paths is lower than the input, the power is said to benon-regenerative. In the regenerative power scheme, sincethere are two paths, situations can arise:? The power through the fixed path is greater than theinput power (mechanical regenerative).? The power through the variable path is greater than theinput power (variable regenerative).Kress 7 of John Deeres Technical Center, laid out thefundamentals which explain how this type of transmissionoperates, but there was no series production for tractors formany years. Recently, CVT transmissions and power splithave started to be used in the automobile industry, forimplementation in hybrid vehicle transmissions 19 as wellas in agricultural tractors. Renius 13, Renius and Resch14, Renius et al. 15 have explained and commented onexisting tractor CVT transmissions. Hsieh and Yan 5,Sheu et al. 17, Lu 9, Shellenberger 18, Mangialardiand Mantriota 10,11, Mantriota 12 and Go mez 4 haveFig. 1. Types of CVT transmissions with respect to the power flow. CVU:continuously variable unit (variator).P. Linares et al./Journal of Terramechanics xxx (2010) xxxxxx3ARTICLE IN PRESSPlease cite this article in press as: Linares P et al., Design parameters for continuously variable power-splittransmissions using planetaries with 3 active shafts, J Terramechanics (2010), doi:10.1016/j.jterra.2010.04.004studied power flow and performance under different oper-ating conditions. Studies made in transmissions providedwith belt mechanical variators prove that those with sum-ming planetaries render a better mechanical performance.In order to compare variators which are hydrostatic trans-missions, they must be equal and only the position of thePGT can be changed. This is not true in commercial trans-missions, because those with divider planetary transmis-sions have a hydrostatic element which is much moresophisticated (variable displacements unit, type bent-axishydraulics units and very large displacements and offsetangles). On the other hand, although the PGT is moresophisticated and they have several maneuvering elements,in summing planetary transmissions there is a simpler var-iator, with conventional hydraulic units. As a result, com-paring performances between the two types is not easy.Fig. 2. Types of commercial hydro-mechanical power-splitting CVT transmissions. HMT: hydro-mechanical transmission. PGT: Planetary gear train, ne:rotation in CVT input shaft, no: rotation in CVT output shaft, nem: rotation in mechanical input shaft in PGT, nom: rotation in output shaft in PGT, n1:rotation rate in shaft 1 of the variator (connected to the coupling).Fig. 3. Possible power flow in different operation modes. Up: dividerplanetary; down: summing planetary. (a) The power flow produces splitfunction. (b and c) The power flow leads to power recirculation. PGT:planetary gear train; VU: variator. Lu 9.4P. Linares et al./Journal of Terramechanics xxx (2010) xxxxxxARTICLE IN PRESSPlease cite this article in press as: Linares P et al., Design parameters for continuously variable power-splittransmissions using planetaries with 3 active shafts, J Terramechanics (2010), doi:10.1016/j.jterra.2010.04.0044. Elements of a power-split CVT with 3 active planetaryshaftsThe basic elements of a CVT transmission are (Fig. 2):? CVT unit input shaft (e). Rotation rate: ne? CVT unit output shaft (o). Rotation rate: no? Coupling or junction: 2-shaft node:sOne connected to the variable path.sOne connected to the mechanical path.? Planetary gear train (PGT): Node with, at least, 3active shafts:sMechanical input shaft to the PGT (em). Rotationrate: nem.sMechanical output shaft(s) from the PGT (om).Rotation rate: nom.sShaft connected to the variable path, called floatingshaft (f). Rotation rate: nf.? Variator (CVU: continuously variable unit): with 2shafts:sShaft 2: Connected to the floating shaft (rotation raten2).sShaft 1: Connected to the coupling (rotation rate n1).? Internal mechanical transmissions:sConnection between PGT and variator (i2).sConnection between variator and coupling (i1).sIn the mechanical path (im).5. Parameters for power-split CVTs with 3-shaft planetariesIn order to understand the operation of CVT transmis-sions, it is useful to define a series of parameters by whichthey are characterized. The famous paper of Kress 7 con-tains (besides other systems) the complete model of power-split systems with 3-shaft standard planetaries. The authorsdeveloped their parameter study on this basis, howeverthey did so with structures which contain an additionalratio of gear wheel(s) between the planetary and the secondjunction point. This enlargement of the basic structures byimcan better accommodate commercial power-split sys-tems with internal transmissions between planetary andjunction point. Definitions of internal transmission ratiosare given by Fig. 2 based on the methodology of Kress 7:? Transmission ratio in the mechanical path of the PGT:Rt.? Transmission ratio in the floating element of the PGT:Rf.? Transmission ratio in the CVT unit: It.The ratios between the speeds of the PGT shafts areexpressed by the basic speed equations as shown inFig. 2, by means of parameters kmand kf8, which repre-sent the share of torque for the two paths assuming nopower losses. The lockup is the point at which a power-splitCVT transmission becomes purely mechanical, the floatingshaft being stationary and the transmission ratio as thelockup ratio, Rtb. When calculating a CVT transmission,the first step is to analyze the PGT in order to achievethe lockup transmission ratio and the values for parameterskmand kf.Once the ratios for the lockup point transmission andthe floating element are known, we can calculate the trans-mission ratio for the PGT using the following formula,which is valid for all types of transmissions (divider andsumming planetaries):Rt Rtb Rf1 ? Rtb6. Power distribution in a power-split CVT transmissionOnce the lockup transmission ratio is known, we candetermine the distribution of power and its status at anygiven time (Tables 1 and 2).The diagram showing the power distribution curvesallows us to determine the status of the transmission:Non-regenerative (NR); mechanical regenerative (MR)and hydraulic or variable regenerative (VR). In both typesof transmission when the transmission ratio is negative, thepower is regenerative through the hydraulic path (VR).However, the behavior is different in the case of positivetransmission ratio. In divider planetaries, power is non-regenerative up to the lockup transmission ratio, and fromthat point on it is mechanical regenerative. In summingplanetaries, power is mechanical regenerative up to thelockup transmission ratio, and from that point on it isnon-regenerative.The operative status of the transmission can also beshown by means of the diagram in Fig. 4, based on thestudies made by Fredriksen 2. In this model, there areas many vertical axes as shafts contained in the PGT, thatis, input shaft, floating shaft and as many output shafts asit may have. Fig. 4 shows only one output shaft. Thespeed for each shaft is shown, taking the speed relativeto the input shaft. Thus, on the floating shaft we haveindicated the transmission ratio Rfand on the outputshafts, we have indicated the transmission ratio for thePGT when the shaft is active. If we assume that the speedof the input shaft remains constant, at that shaft the sin-gle point is the unit.In Fig. 4, the distance between the different vertical linesis an arbitrary distance, considering the unitary distancebetween the input and the floating shafts. Vertical lines rep-resenting Rtand Rfare placed at a specific distance fromthe floating shaft. This distance is determined by the lockuptransmission ratio corresponding to the PGT when thisshaft is active.Once the organization of the PGT and the variation ofthe transmission ratio on the floating shaft are known,the point of the input shaft is joined to the ends of the linedefined by the transmission ratio on the floating shaft. Thelines thus obtained correspond to the maximum and mini-mum shaft speeds. The intersection of the two lines withP. Linares et al./Journal of Terramechanics xxx (2010) xxxxxx5ARTICLE IN PRESSPlease cite this article in press as: Linares P et al., Design parameters for continuously variable power-splittransmissions using planetaries with 3 active shafts, J Terramechanics (2010), doi:10.1016/j.jterra.2010.04.004the output shafts provides the transmission ratios. Thelockup line is also represented; it is obtained by joiningthe input shaft point to the corresponding stationary float-ing shaft. We can easily identify the operation status of thetransmission on this diagram. Assuming that Fig. 4 corre-sponds to summing planetary transmission; the differentfields of operation have been represented. For the rangeof variation of the transmission ratio drawn on the floatingshaft, the transmission would operate one half of the rangein the mechanical regenerative zone and the other half inthe non-regen