行星齿轮传动_CVT机构的参数模型和分析

行星齿轮传动2CV T 机构的参数模型和分析Param etr ic M odeli ng and Analysis of A planetaryGear -CVT M echan is mV ictor H .M ucino 3J am es E .Sm ith3B en Co w an 33M a rek Km icik ie w icz33[摘要]本文研究行星齿轮传动和无级变速器(CV T )综合功能,用太阳轮和齿圈与可变节距的带轮相连接形成一个循环功率控制元件。

该机构简单,工作时不需离合器。

参数方法是用一个数学模型去完成参数灵敏度分析。

优化过程的一个特徵参数是系统最有影响的参数和功能比,以它为基础去估算可变传动和功率控制元件。

用三种不同的传动比和二个独立设计参数可完全确定系统的结构。

这些是:行星齿轮系速比(F g )、CV T 传动速比(F c )和控制输出齿轮速比(F gc )。

二个独立参数是:a ,行星轮转臂、太阳轮、内齿圈和b ,控制齿圈和输出齿轮其中之一的半径。

[ABSTRACT ]　T he m echan is m con sidered here ,com b ines the functi on s of a p lanetary g ′ear train and acon tinuou sly variab le tran s m issi on (CV T )system ,th rough a circu lating pow er con tro l un it ,w h ich resu lts by connecting the sun 2gear shaft and the ring 2gear ro tati on th rough a variab le p itch pu lley system .T he m echan is m is si m p le and does no t requ ire clu tches fo r its operati on .A param etric app roach is u sed to generate a model that can be u sed to perfo rm param etric sen sitivity analysis .In the op ti m izati on p rocess ,a param etric characterizati on is m ade based on the mo st sign ifican t param eters and functi onal rati o s of the system to evaluate the perfo rm ance of the variab le tran s m issi on and pow er con tro l un it .T h ree differen t tran s m issi on rati o s and tw o independen t design param eters fu lly define the configu rati on of the system .T hese are :the p lanetary gear train rati o (F g ),the CV T tran s m issi on rati o (F c ),and the con tro l to ou tpu t gear rati o (F gc ).T he tw o independen t param eters can be selected from the radii of tw o group s of elem en ts (one from each ),that include a )the p lanetary gear carrier ,the sun gear ,the in ternal ring gear and b )the con tro l ring gear ,and the ou tpu t gear . 关键词:行星传动　无级变速器CV T 参数模型　功率分流　功率反馈 Key w o rds :p lanetary gear train con tinuou sly variab le tran s m issi on CV T Param etric modelingpow er sp lit Pow er 2Feedback3W est V irginia U niv .33CK Engineering引言行星齿轮机构和无级变速箱的综合已有很多成功的应用实例,本文仅述及由行星齿轮系和CV T 直接组合提供变速的传动装置。

这两个主要部件(行星传动和CV T )的综合特性是不要求采用离合器和链传动,这种的机构的三种主要结构简称为“行星2CV T ”,一般布置为二个功率反馈和一个功率分流。

本文研究的系统如图1所示,按其特徵参数确I n troductionP lanetary gear train m echan is m s and con tinu 2ou sly variab le tran s m issi on s have been u sed suc 2cessfu lly in m any types of app licati on s .T he m echa 2n is m p resen ted in th is paper u ses on ly a p lanetary gear train system and a CV T un it directly connect 2ed to p rovide a variab le tran s m issi on un it .T he com b ined featu res of the tw o m ain componen ts (p lanetray and CV T )do no t requ ire the u se of clu 2图1　‘功率反馈’行星传动2CV T机构结构F ig.1　P lanetary2CV T m echan is m configu rati on fo r‘Pow el2Feedback’r p-行星齿轮节径rediu s of the p lanet gear;r a-转臂半径radiu s of the arm carrier;r s-太阳轮节径radiu s of the sun gear;r ri-内齿圈节径radiu s of the in ternal ring gear;r r-外齿圈节径radiu s of the ex ternal ring gear;r0-输出轴齿轮节径radiu s of the ou tpu t shaft gear;r I2CV T滑轮外径ou ter radiu s of the CV T pu llery;r c-行星带轮节径p itch radiu s of p lanet sheave;r2-输出带轮节径p itch ra2 diu s of ou tpu t sheave定总的几何外形动。

三个重要的传动比是:1,行星齿轮传动比F g,该传动比确定于太阳轮节径与内齿圈节径之比;2,无级变速速比F c,该传动比确定于CV T主、从动滑轮的节径比;3,控制齿圈与输出齿轮比F gc,该传动比确定于输出齿轮节径与外圈(控制齿轮)半径之比。

一般行星齿轮传动有三个主要转动件(行星架,太阳轮和内齿圈),具有二个自由度。

应给定二个转动件的运动来确定第三构件的运动。

其图解实例见图2。

太阳轮轴用一惰轮与输出齿轮相连,同时输出轴用固连于行星传动圈齿轮直接与行星传动相连。

这样的安排就减少了一个自由度。

所以输入连杆足以确定所有构件的运动,输出运动可以或者由太阳轮或者由中间轴直接确定。

现在,如果太阳轮轴和输出轴之间连接惰轮由CV T的一个滑轮代替,将形成图1所示的变速比机构。

带入系统的一个附加自由度可控制获得输入和输出予期规定的速比。

这是一个运动自由度和一个控制自由度造成的结果。

tches and chaindrives.T h ree m ain configu rati on s of th is m echan is m dubbed si m p ly“P lanetary2 CV T”,are p resen ted in tw o pow er feedback and one pow er sp lit fo rw ard general arrangem en ts.T he system con sidered here is dep icted in F ig. 1,along w ith the characteristic param eters w h ich define the overall geom etric configu rati on.T h ree rati o s of in terest are:1)the p lanetary gear train rati o(Fg),defined as the rati o of the sun gear p itch radiu s to the in ternal ring gear p itch radiu s,2)the con tinuou sly variab le tran s m issi on rati o(Fc),de2 fined as the effective p itch radii rati o of the CV T sheaves and3)the con tro l ring gear to ou tpu t gear rati o(Fgc),defined as the rati o of the ou tpu t gear p itch radiu s to the ou ter ring(con tro l gear)radiu s.Generally,a p lanetary gear train has th ree m ain ro tating elem en ts(p lanet gear carrier,sun gear and the in ternal ring gear)w ith tw o k inem atic degrees of freedom.P rescribed mo ti on s fo r tw o of the ro tating elem en ts are requ ired to determ ine the mo ti on of the th ird elem en t.In system s con tain ing a con tro l un it,one of the p rescribed mo ti on s is m ade dependen t on the first one by m ean s of con2 necting elem en ts,fo r examp le in the system show n schem atically in F ig.2,the sun gear shaft connects to the ou tpu t gear shaft by m ean s of an idler gear, w h ile the ou tpu t shaft is directly connected to the p lanetary gear train by m ean s of an ou tpu t gear and a con tro l gear so lidly attached to the p lanetary ring gear.T h is arrangem en t reduces one k inem atic de2 gree of freedom,so that the mo ti on of the inpu t link is sufficien t to define the mo ti on of all the ro2 tating componen ts.It shou ld be no ted that the ou t2 pu t mo ti on can be taken directly from either the sun gear shaft o r the coun tershaft.N ow,if the idler gear connecti on betw een the sun gear shaft and the ou tpu t shaft is rep laced by a CV T pu lley un it,the resu lting m echan is m yields a variab le speed rati o as the one show n in F ig.1.A n additi onal degree of freedom is b rough t in to the system w h ich allow s con tro l to be exerted on the p rescribed velocity ra2 ti o betw een the inpu t and ou tpu t shafts p revi ou sly indicated.T he resu lt is a m echan is m w ith one k ine2 m atic degree of freedom and one con tro l degree of freedom.图2　带有‘功率反馈’和固定速比的行星齿轮传动F ig.2　P lanetary gear train system w ith‘Pow er2Feedback’and fixed speed rati o 数字模型的描述行星传动的运动特性公式可以如下述公式用角速度来表示:W Ia W fa=(W I-W a) (W f-W a)(1) 式中W Ia-相对转臂的“末”齿轮角速度;W f a是相对转臂的“首”齿轮的角速度,W I、W f和W a分别是‘末’和‘首’齿轮以及转臂的绝对角速度。