DESIGN OF MOTORCYLE ACTIVE CHASSIS GEOMETRY CHANGE SYSTEM

Transcription

1 DEIGN OF MOTORCYLE ACTIVE CHAI GEOMETRY CHANGE YTEM Jakub Šmiraus 1, Micha Richář 2 ummary: Modern moorcyces have a number o eecronic sysems supporing heir driving sabiiy. These are usuay adoped souions used in auomobies. However, he idea o rying o aec he driving sabiiy wih he use o up-o-now changeess parameers such as wheebase or rai is quie new. uch an innovaive souion o moorcyce suspension wih variabe geomery dependen on driving condiions was designed in hesis by Jakub Šmiraus and consruced a he Insiue o Transpor VŠB - Technica universiy o Osrava under ueage o Mc Micha Richář. Key words: Moorcyce dynamics, moorcyce suspension, variabe suspension, variabe rai, rai, acive moorcyce geomery chassis. INTRODUCTION During deveopmen o he irs moored bicyces, e.g. a seam powered Veociped Michaux-erraux, emphasis was pu on neiher comor nor driving sabiiy. Ony a beginning o 20h cenury, when inerna combusion engine has been paened by Dr. Oo, his assisan G. Daimer commenced o inquire ino issues o driving sabiiy and handing o a singe-rack vehice in paricuar. ince hen, moorbike has been inexoraby deveoped ino more and more perec machine wih driving dynamics surpassing ha o majoriy o conemporary cars, which resued in occurrence o periods when engine power signiicany ouperormed capabiiies o chassis. A signiican breakhrough in moorcyce chassis design ook pace a he end o 90s, when new maerias, e.g. auminium aoy or various composies, were uiized. This brough abou up-o-now unprecedened srengh whie susaining or even decreasing weigh o paricuar pars. I was hen, when deveopmen o as ye perecy conroabe and sae moorcyces was made possibe. These days, new chassis design, damping and spring eemens as we as brake sysems wih braking assisan souions are perpeuay modernized. The aes innovaion in he ied o moorcyces is an appicaion o eecronics o moorcyce chassis in he orm o eecronic sabiizaion o i and engine power reguaion dependen on driving condiions. 1. MOTORCYCLE DIMENION Typica eaures o singe-rack vehices have aways been a good conroabiiy, ie road resisance and an easy handing. The above menioned conroabiiy and sabiiy in a 1 Ing. Jakub Šmiraus, VŠB - Technica Universiy o Osrava, Facuy o Mechanica Engineering, 17.isopadu, 15, Osrava-oruba, Te.: , E-mai: kubik.smiraus@seznam.cz 2 Ing. Micha Richář, VŠB - Technica Universiy o Osrava, Facuy o Mechanica Engineering, 17.isopadu, 15, Osrava-oruba, Te.: , E-mai: micha.richar@vsb.cz Šmiraus, Richář: Design o moorcye acive Chassis Geomery Change ysém 279

2 sraigh-ahead driving or pich is deermined especiay by raio o chassis dimensions, consrucion and an overa seering geomery. ource: auhors Fig. 1 - Main parameers o moorcyce chassis geomery Rake (α) oin o whee conac (1) eering axis and ground inersecion (2) Trai(n) Whee-base () Cenre o graviy ocaion (h T, ) Rake ange Rake ange o he ron ork indicaes he ange beween he seering axis and he ground pane. A smaer rake ange o he ron ork resus in a greaer sabiizing eec on he ron ork. The rake ange (ange o seering axis) ies wihin abou 24 o 30 o he ground. eering axis and ground inersecion oin o conac wih he ground is indicaed as whee axis inersecion perpendicuar o he base o a saionary bike a a poin o heir inersecion. Trai Trai is he disance beween eering axis and ground inersecion and he oin o whee conac. Trai has a signiican impac on he sabiiy and handing o a moorcyce. Whee-base Wheebase is he disance beween he roaion axis o he whees in a sraigh-ine drive. Cenre o graviy ocaion Cenre o graviy is deermined by verica and horizona posiion. Wha is more imporan han examining is posiion on an unoccupied bike is observing he changes wih an increasing oad. ource: (2) The driving characerisics can be signiicany aeced by modiicaion o he basic parameers. Thereore, i we wan o cusomize he driving sabiiy o an aready consruced moorcyce, we have he oowing opions. We can adjus he posiion o cenre o graviy. Šmiraus, Richář: Design o moorcye acive Chassis Geomery Change ysém 280

3 This can be achieved by change o a riding posure, which is, however, imied by pacemen o conro and suppor eemens o he moorcyce. houd a wo-person crew drive he vehice, he cenre-o-graviy posiion shis noaby. Neverheess, hese changes are no aways easy o conro propery because i is impossibe o encompass a he variey o passengers weighs. Furher parameers o chassis are: whee base, rai, rake or seering axis ange. These dimensions are se, bu i hey were adjused according o he driving condiions he overa driving sabiiy as we as he seering response o he iniiaive o he driver coud be inuenced. Lenghening o boh wheebase and rai woud resu in an increased sraighine sabiiy, which woud hep o improve he comor o ong disance driving a higher speed. The opposie is assumed o be rue as we. horening he aer menioned parameers woud ead o a decreased sabiiy, ye a he same ime a beer handing, which is advanageous in he condiions o e.g. urban raic. uch is he heory o hese eaures impac on he moorcyce handing and driving characerisics. 2. INGLE-TRACK VEHICLE DYNAMIC 2.1. The equaion o moorcyce moion The same rues and aws can be appied o he moion o a oher vehices. Moorcyce moion ca be deined by he same equaion o moion as auomobie or a rain moion. F = O K V R T (1) M r d K = F K = O V R = F e r d ρ + cx v 2 2 x r (2) Under he condiions O,O T,O R = 0 F K. O. O. O V O R.. O T Driving orce(ower) [N] Roing resisance [N] Gradien resisance [N] Air resisance [N] Acceeraion resisance [N] Draw resisance [N] I is poiness o dea wih paricuar resisances, saed in he above equaion o moion (1), in his arice. The ex covers ony he resisances which are expeced o be aeced by he inervenion o an acive change in seering geomery. The roing resisance remains unchanged, bu aer i is going o be menioned as one o he resisances ensuring he sraighine sabiiy. Gradien resisance, greay dependen on he rack characer an exerna acor wi be considered as unchanged as we rom he poin o view o acive change in seering Šmiraus, Richář: Design o moorcye acive Chassis Geomery Change ysém 281

4 geomery. Nex in he equaion (1), here is he air resisance, whose main componen is a quadraic veociy v r, an inpu acor o driving. Anoher exerna acor is he densiy o air ρ, deermined by he driving condiions. The oowing wo ones, i.e. he coeicien o air resisance c x and he wind area x, are expeced o aer aer he geomery change. The benei, ahough jus a minor one, o such a change is he decrease o he produc o hese wo variabes when he speed increases. This aso means a reducion o air resisance a higher speeds. eemingy, an acceeraion resisance is no aeced by he chassis geomery change, which is ony pary rue. This resisance is no aeced by he chassis geomery change uness we consider he maximum acceeraion. This impies ha by changing he wheebase and hus changing aso he disribuion o oad on each whee i is possibe o inuence he vaue o he maximum acceeraion or deceeraion o moorcyce. When we enghen he wheebase we are abe o shi he posiion o he cenre o graviy. In case o a pursui o a maximum posiive acceeraion he cenre o graviy sha be moved rom he rear whee o he ron one. Thus we can ind he exac imi o he rear whee sip by boh he ack o a oading orce on he ron whee and he moorcyce wheeing due o he shi o he cenre o graviy o he back. A deceeraion he eec wi be exacy he opposie. A inensive braking he rear whee is reieved, which eads o oss o sabiiy or migh even cause a vehice ro. This siuaion is represened by he equaion beow Maximum posiive or negaive acceeraion Fig. 2 - Acceeraion o he moorcyce ource: auhors Šmiraus, Richář: Design o moorcye acive Chassis Geomery Change ysém 282

5 F. G. G. m. g. a max = F. h + F. h = m. a g. = h max. h = 0 F = 0 (2) condiion : μ. F ( + amax. ϑ ). G g (3) F p, F z. Dynamic whee oad [N] F.. Ineria orce [N] G...Vehice oa weigh [N] h Cener o graviy heigh [m].. Whee-base [m] p, z Cener o graviy ocaion [m] a max...maximum acceeraion [m.s -2 ] g. Graviaiona acceeraion [m.s -2 ] The correaion shows ha he acceeraion vaue aecs he raio /h. When he cenre o graviy moves owards he ron, boh he vaue o and he heoreica maximum acceeraion increase. Fig. 3 - Braking o he moorcyce ource: auhors Šmiraus, Richář: Design o moorcye acive Chassis Geomery Change ysém 283

6 F. G. G. m. g. b max g. = h = F. h + F. h = 0 = m. b max. h F = 0 (4) condiion : μ. F F X = F F X F xp.adhesive orce [N] µ...coeicien o adhesion m... Vehice oa mass [kg] b max...maximum negaive acceeraion [m.s -2 ] (5) 2.3. Eec o a geomery change on he direciona sabiiy o he moorcyce The sabiiy o he moorcyce is secured by severa momens and eecs which resu rom he moion o he vehice or is pars, one o hem being a reversibe handebar orque. I dispays as an ani-vibraion handebar sabiiy and ensures a sraigh-ahead driving. Is componens, namey momen arm a and orce F x1, oow rom he beow saed cacuaion (6) and (7). Reurn momen arm a a = n. gδ (6) eering reurn momen M V M = Fx. a M V V = O 1. a (7) Šmiraus, Richář: Design o moorcye acive Chassis Geomery Change ysém 284

7 Fig. 4 - eering reurn momen ource: auhors Fx 1...Braking orce, ro resisance [N] α... eering axis ange [ ] n... Fron rai [m] a... eering reurn momen [m] δ... Ange o seering [ ] Mv... eering reurn momen [N.m] eering axis and ground inersecion Tire conac area I is obvious ha he higher ongiuda orce F x on momen arm a increase he seering reurn momen (ig.4). The correaion (6) ceary shows he impac o he rai size n on he reurn momen arm a. Oher aspecs o driving sabiiy are gyroscopic momen and rear whee direciona dierence a deormaion o he moorcyce rame. Fas-roaing whee wih is own very high sabiiy becomes a gyroscope. I sponaneousy mainains is posiion o roary pane. As soon as he gyroscope is deeced rom he roary pane wih exerna orce a reacion o he Šmiraus, Richář: Design o moorcye acive Chassis Geomery Change ysém 285

8 deecive orce, which is a 90 o ange wih he origina piching pane, is creaed. The orces increase wih an increasing ange speed. The described reacion in such a ywhee o an axis ean is caed precession. In oher words, i we change he ange o he axis o he pace, he piching momen o he roaing gyroscope wi have eec on he smaer momen arm. 3. DEIGN OF THE CHAI During designing he whee suspension, irs o a he mode and ype o a moorcyce was deined. For pracica apicaion he ouring moorcyces or superspors o he uure are mos useu or geomery changing sysem. As a paorm or he design an od superspor Kawasaki XR 400 L was chosen. An auminium rame was disassembed and ransmied as a 3D mode ino soware Auodesk Invenor, where a he modiicaions in he whee suspension equipped wih a seering head were projeced. The emphasis was pu on mainaining srengh and siness o he rame. Aready during designing o he suspension o seering head, i was imporan o consider he uure acuaor or swinging moion o seering head. evera possibe opions o consrucion were designed, rom which he mos reaisic ones are shown beow on igure no. 5. ource: auhors Fig. 5 - roposas o change he ange o he seering axis o a moorcyce Based on he resus o decomposiions o oading orces and he assessmen o saey as we as compacness o he whoe design he souion no. 4 was seeced ou o he above dispayed ones. An anaysis o srengh and siness o he rame has been aso carried ou. The resus were compared wih deormaions in areas o high sress. The rame wih opiona ron suspension geomery seings evinced ower orsion siness and he areas o high sress were concenraed raher in head sock han he poins o inererence in he origina design. The areas o high sress concenraion (ig.6) were addiionay reinorced wih ie weds. I was necessary o carry ou a cacuaion o chassis and o check he connecion o he sressed pars, as regards cu or deormaion caused by pressure. A numerica cacuaion o suspension sha has been made. Consequeny, i was designed wih he generaor o componens in Auodesk Invenor and aer ha he resus were compared o minimize he possibiiy o error in cacuaion o he suspension base. Šmiraus, Richář: Design o moorcye acive Chassis Geomery Change ysém 286

9 ource: auhors Fig. 6 - ress during orsion oad o chassis (Ansys Workbench v11) rior o manuacuring o he par, aso he acuaor o moion had o be designed. To achieve a ow weigh gain o moorcyce and is propusion as ie space-demanding as possibe i was decided upon an eecromechanica sysem. I was made o a mechanica ransmission gear and an eecric moor, powered by board ne. A speed reducor was uiised in he mechanica gear, which made i possibe o use a high speed eecric moor wih sma dimensions whie mainaining he required oupu orque o gearbox. Anoher componen o he ransmission gear was a mechanica inear acuaor, convering roary moion ino inear moion, which is necessary or seing he correc ange o he seering axis. The advanage o uiizaion o he mechanica inear acuaor (ig.7) is he appicaion o a se-ocking propery, because i is no necessary o use a brake, which heps o preven rom a change o he ange o he seering axis a enormous oad o he suspension. The whoe consrucion ensures absorpion o orces generaed during he driving o he vehice in he base o suspension. Thereore, anoher reducion o he eecric moor ransmission gear size, was made possibe. Eecric moor ransmission gear now oaded ony wih he eecric moor orque. Fig. 7 - Composiion o Linear acuaor ource: auhor Šmiraus, Richář: Design o moorcye acive Chassis Geomery Change ysém 287

10 The ina assemby in Auodesk Invenor proved ha designed componens are abe o creae a compac and unciona suspension uni. Driving ess on moorcyce wih designed suspension, caed acive chassis geomery change sysem, are now conduced. CONCLUION The designed sysem wih seering geomery changes migh be a pioneering idea in consrucion o he 21s cenury moorcyce chassis. The rai adjusmen aong wih changes in wheebase and ground cearance o he bike open up many opions in he ied o negaive eecs reguaion resuing rom he dynamic characerisics o moorcyce moion. Wih he inroducion o composie maerias and aes auminium aoys, here come he possibiiies o suspension consrucion wih variabe vaues o seering axis ange or wheebase. The main idea in he consrucion o he designed suspension is o smoohy change he parameers o he chassis during he drive. This woud be done manuay by he driver in he irs generaion and auomaicay, depending on he opima chassis seup, in he oowing one. In he uure generaions, he whoe sysem coud be uy auomaed, in which case i coud coaborae wihou diicuy wih he above menioned aready uiized sabiiy and assisance sysems. This connecion woud be simiar o CAN-bus sysem o auomobies, where paricuar sysems are conneced o a common bus and managed by he cenra conro uni (ECU). ACKNOWLEDGEMENT This arice was suppored by he projec no. 2011/58, and designed souion is proeced by uiiy mode no. UV 22413: REFERENCE (1) ŠMIRAU JAKUB: Konsrukční řešení sysému akivní změny geomerie moocyku. Osrava, Dipomová práce. VŠB Technická universia Osrava (2) VLK FRANTIŠEK: Teorie a konsrukce moocyků 1. Brno IBN (3) Ing. B. ďánský, Ing.. Jan: Auomobiy 1. Brno: Avid s.r.o (4) DVOŘÁK MIROLAV, VLK FRANTIŠEK, LOÍK VÁCLAV: ČEKO-ANGLICKO- NĚMECKÝ LOVNÍK AUTOMOBILOVÉ TECHNIKY. ELK Brno (5) J. G. TRMAL: Rozbor exrémních dynamických savů srojů a mechanismů, ČVUT raha IBN Šmiraus, Richář: Design o moorcye acive Chassis Geomery Change ysém 288