资源目录
压缩包内文档预览：
编号：23351699
类型：共享资源
大小：2.77MB
格式：RAR
上传时间：2019-11-09
上传人：qq77****057
认证信息
个人认证
李**（实名认证）
江苏
IP属地：江苏
30
积分
- 关 键 词：
-
摩擦
机械
无级
变速器
结构设计
- 资源描述：
-
摩擦式机械无级变速器结构设计,摩擦,机械,无级,变速器,结构设计
- 内容简介：
-
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: +34 605 445 597./locate/jterraAvailable 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-regenerative zone.As an example, Fig. 5 shows the CVT unit of the ZF-Eccom 1.5 box, which is included with the tractor DeutzAgrotron TTV. It is evident that it is summing planetarypower-split transmission, with a compound PGT madeup of three interconnected single PGTs. The variator isthe hydrostatic transmission, formed by one variable dis-placement unit (unit 1) and another fixed displacement unit(unit 2). The PGT has 5 shafts, one for the mechanical pathinput (the ring-gear of the first PGT), the floating shaft (thesun of the first PGT) and 3 possible output shafts, of whichat any given variator ratio, only one is active, thus makingthe box a “3 active shaft”-type. In series with this CVT unitis a range box equipped with 4 clutches which, in accor-dance to the desired speed, selects one of the possible out-put shafts (of the CVT units three output shafts, one isused in the two even-numbered ranges). The result is 4ranges in series, in which the maximum speed for eachone matches the minimum speed of the next. Fig. 5 showsthe CVT parameters corresponding to each of the 3 possi-Table 1Power distribution (X) in CVT transmissions.Power distributionOutput coupled planetary (divider)Input coupled planetary (summing)Xmt NmNeg1RtRtbXmt NmNeg1RtbRtXvt NvNeg1 1 ?RtRtbXvt NvNeg1 1 ?RtbRtNe: input power in CVT unit. Nm: power in mechanical shaft. Nv: power in variable shaft.Xmt: power distribution in mechanical path. Xvt: power distribution in variable path. g: efficiency.Rt: transmission ratio in the mechanical path of the planetary system.Rtb: transmission ratio in the lockup point.Table 2Power distribution based on transmission ratio Rt.Rt 1VRRt RtbMRXvt 0MR0 Rt Rtb0 Rt RtbNR0 Xvt RtbPower distribution in CVT transmissions with 3 active 4 planetary shafts. Mem: torque in mechanical input shaft to the PGT. Mom: torque in mechanicaloutput shaft to the PGT. Mf: torque in shaft connected to the variable branch, called floating shaft.VR: variable regenerative power flow.MR: mechanical regenerative power flow.NR: non-regenerative power flow.N: power.Ne: input power in CVT unit.PGT: Planetary gear train.6P. 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.2010.04.004ble configurations of the PGT and Fig. 6 shows the speedsfor the three output shafts.7. Design of 3 active shafts power-split CVT transmissionsIn order to achieve the desired objective (a certain rangeof transmission ratios), once the type of transmission hasbeen established, there are two remaining design parame-ters: The ratio for lockup transmission Rtband for thefloating shaft Rf, which depends on that of the variator,Rv(n2/n1) and on the CVT units internal transmissions3 (Table 3).The lockup transmission ratio depends on the CVTparameters, and these depend on two characteristics:? The configuration of the PGT, which determines theinput (im), output (om) and floating shafts.? The dimensions of the PGT, which determine k which isthe ratio of ring gear teeth and sun gear teeth.Fig. 5. kmand kfparameters in CVT ZF-Eccom 1.5 transmission (Deutz Agrotron TTV).Fig. 4. Transmission ratio diagram in CVT unit. NR: non-regenerativepower flow. MR: mechanical regenerative power flow. VR: variableregenerative power flow.P. Linares et al./Journal of Terramechanics xxx (2010) xxxxxx7ARTICLE 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.2010.04.004Summing up, the design parameters, once the type oftransmission has been established, are:? Organization of the CVT unit: internal ratios i1, i2, im? PGT of the CVT unit: type of PGT (single orcompound) and its configuration (em, om, f, k, km,kf, Rtb)? The variator (Rvand, consequently, Rf)Fig. 7 shows the flow diagram for the design of power-splitCVT transmissions with 3 active shafts.8. Design application of a CVT transmission model fortraining purposesWith the aim of preparing teaching material which rep-resent and demonstrate concepts of power-split CVT trans-Fig. 6. Speed diagram in the Planetary Unit in ZF-Eccom 1.5 transmission. n: Rotaion speed; ne: rotation speed in CVT input shaft.Table 3Transmission ratio of the floating shaft Rfin the two types of three shaft power-split CVT transmission.Transmission ratio of the floating shaftDivider planetarySumming planetaryRfi2?im?Rtb?Rvi1?i2?im1?Rtb?RvRfi2?imi1? RvRvn2n1Different shafts placed in the CVT unit in divider planetary transmissions (left) and summing planetary transmissions (right). n1: rotation rate in shaft 1 ofthe variator (connected to the coupling). n2: rotation rate in shaft 2 of the variator (connected to the floating shaft). nm: rotation rate in shaft betweenplanetary gear train and coupling. PGT: Planetary gear train.8P. 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.2010.04.004missions, a model has been designed by the “Tractors andTillage” Research Groups at the Polytechnic University ofMadrid (Figs. 810). This model works with a 3 activeshaft PGT and has the following features:? Choice between the two possible arrangements (inputand output coupled).? Mechanical belt variator.? Single PGT (Zc= 58; Zp= 20 ; k = 2.9) (Fendt VarioTransmission series 400).? Mechanical inverter.In this case, the type of transmission is already set (splitpower), as well as the dimensions and type (single) of thePower splitArrangementN active shaftsEngine CVT YESNo Shaft to shaft 3Rv4Bridge type DIVIDER SUMMING VARIATORRfConfigurationem om fZCZP km kfRtbRtkm kfRtbInternal transmissions : i1, i2, imInternal transmissions : i1, i2, imRfRtDimensionsPlanetary Gear Train Configurationem om fZCZP DimensionsPlanetary Gear Train Fig. 7. Design diagram of three active shafts power-split CVT Transmissions.P. Linares et al./Journal of Terramechanics xxx (2010) xxxxxx9ARTICLE 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.2010.04.004PGT. To choose the type of configuration, Fig. 8 shows therelationship between the dimensions of the PGT (repre-sented by k) and the lockup transmission ratio in the sixpossible configurations of the single PGT.Divider or summing configurations are achieved by asliding gears wheel selector as shown in Fig. 9, the equiva-lent configurations (Table 4) between both arrangementsmust be considered. Configuration III is chosen, in whichthe lockup transmission ratio is positive. It correspondsto an arrangement used in commercial transmissions, suchas Vario, present in Fendt tractors, and Dyna-VT, in Mas-sey Ferguson, which has an input coupled planetary config-uration, and was presented by Sheu et al. 17, the latterfeaturing a mechanical variator.For the dimensions of the PGT available (k = 2.9), thelockup transmission ratios were 3.9 and 0.256 for dividersumming planetary arrangements respectively. The varia-tor is mechanical, belt-type, and with a variation range(Rv) between 0.7 and 2.5. All the internal transmissionsin the model have a value of 1, including the mechanical in-verter. With these values, the possible transmission ratiofor the input coupled planetary goes from ?0.92 to ?3.3when operating with variable regenerative power statusand from 0.63 to 1.23 when operating in the non-regenera-Fig. 8. Relationship between k and Rtbin the six possible connection arrangements in a simple planetary. Rtb 0 and k 1.5.10P. 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.2010.04.004tive zone. In the case of the output coupled planetaryarrangement, the values are ?1.8 to ?0.3 in variable regen-erative and 0.81.6 in non-regenerative. Operation in themechanical regenerative zone is not carried out in eitherof the two arrangements.9. Mixed CVT transmissionsThe authors propose to use the term “mixed CVT trans-missions” for transmissions with a shiftable combination ofdifferent modes such as shaft-to-shaft (direct) variatormodeandapowersplitmode.Thementioned“Responder” 20 worked with a hydrostatic variator in afirst direct shaft-to-shaft mode for driving offand reversingand a second mode with input coupled power split forcruising. Kress 6 and Browning 1 analyzed mixed CVTtransmissions with a mechanical variator.Fig. 9. First design of the transmission model 3. 14 are places for positionning torsiometers.Fig. 10. CVT Transmission model designed at designed by the “Tractorsand Tillage” Research Group at the Polytechnic University of Madrid.Table 4Equivalent configurations between divider and summing planetary arrangements 3.Divider planetaryEquivalentconfigurationSumming planetaryemfomBasic configuration of the singlePGTBasic configuration of the singlePGTemfomCPPS1I5PSPCPCPS2II3PSCPPSCP3III2PCPSCPSP4IV6PPSCPSPC5V1CPPSPPSC6VI4CPSPP: sun gear; C: ring gear; PS: carrier; em, om and f see Fig. 2.I, II, III, IV, V and VI: different arrangements of em, f and om in a PGT.P. Linares et al./Journal of Terramechanics xxx (2010) xxxxxx11ARTICLE 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.2010.04.004This type of transmissions has also been discussed bySheu et al. 17 for use in motorcycles, Fig. 11. It allowstwo possible modes. When the clutch Ca goes into action,it is a power split mechanicalmechanical CVT, with beltvariator and summing PGT. When Cd (and not Ca) isengaged, the path to the sun gear of the PGT is interruptedand the transmission becomes a non-split CVT with amechanical belt drive variator. It should be mentioned,that this power-split system does not always have the mainobjective of increasing efficiency rather its objective is toexpand the band width of speeds versus zero or even cross-ing zero to reverse 6,1,16.The transmission provided in the John Deere 30 seriestractors can also be called a mixed transmission (Fig. 12).It has clutches in its paths and it operates in a sequentialmanner as an input coupled-bridge type planetary (theFig. 11. Mixed CVT transmission 17.Fig. 12. Mixed CVT transmission in AutoPowr John Deere 8030 agricultural tractors simplified structure “forward”.12P. 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.2010.04.004sequence being repeated twice in the forward speedrange).10. ConclusionsThis research has been written with the aim of laying outa set of concepts which would aid in classifying and under-standing CVT transmissions, as well as to present a generalscheme for their depiction in terms of representativeparameters, kmand kf. These parameters represent the dis-tribution of torques on the mechanical and variable pathsand the lockup transmission ratio, which can be calculatedas a function of those parameters.The general diagram for the design of the transmission isoutlined. The design parameters are the characteristics ofthe PGT (dimensions and configuration) that determinethe lockup transmission ratio, as well as t
- 温馨提示:
1: 本站所有资源如无特殊说明，都需要本地电脑安装OFFICE2007和PDF阅读器。图纸软件为CAD,CAXA,PROE,UG,SolidWorks等.压缩文件请下载最新的WinRAR软件解压。
2: 本站的文档不包含任何第三方提供的附件图纸等，如果需要附件，请联系上传者。文件的所有权益归上传用户所有。
3.本站RAR压缩包中若带图纸，网页内容里面会有图纸预览，若没有图纸预览就没有图纸。
4. 未经权益所有人同意不得将文件中的内容挪作商业或盈利用途。
5. 人人文库网仅提供信息存储空间，仅对用户上传内容的表现方式做保护处理，对用户上传分享的文档内容本身不做任何修改或编辑，并不能对任何下载内容负责。
6. 下载文件中如有侵权或不适当内容，请与我们联系，我们立即纠正。
7. 本站不保证下载资源的准确性、安全性和完整性, 同时也不承担用户因使用这些下载资源对自己和他人造成任何形式的伤害或损失。
人人文库网所有资源均是用户自行上传分享，仅供网友学习交流，未经上传用户书面授权，请勿作他用。
川公网安备: 51019002004831号