Maastikusuutlik elektriliikur

Lõputöö käigus püstitas autor omale eesmärkideks projekteerida maastikusuutliku invaskuutri raam koos õõtshoobade ja käändmikuga ja valida sinna juurde vajalikud komponendid. Selleks pidi autor esmalt uurima Eesti Vabariigi seadusi, et saada teada, mis piirangud on pandud erinevatele kategooritatele ning sõidukitele. Lisaks analüüsis autor viite analoogset sõidukit, mõistmaks, mis on nende masinate juures maastikusuutlikuse seisukohast hea, projekteerimise keerulisust ning kui mugav ja lihtne on sihtgrupil neid sõidukeid käsitleda. Lisaks käis autor ka ühe sarnase sõidukiga tutvumas ja sõitmas, et saada paremini aimu, kuidas antud sõidukit projekteerida. Kuna autor ise sihtgruppi ei kuulu, siis tegi ta küsitluse, kus vastas 20 inimest, kes olid eakad või erivajadustega. Küsitlusest sai autor teada, mis soovid ja ootused on inimestel, kelle jaoks oleks sarnane sõiduk praktiliselt asendamatu. Projekteerimine algas baasandmete, nagu skuutri mõõtude, kliirensi, sõiduulatuse ja veoskeemi, paika panekuga. Lisaks ka vajamineva võimsuse arvutamisega. Järgnevalt oli vaja välja valida raami, õõtshoobade ja käändmiku materal. Valides alumiiniumi ja terase vahel valis autor terase tema hinna ja töödeldavuse tõttu. Eriti just viimase omaduse pärast, sest autor tahab sõiduki kodustes tingimustes ise valmis teha. Materjal valitud, oli aeg hakata tegelema projekteerimisega. Esmalt hakkas autor pihta raamist. Raami tegi autor sarnase külastatud skuutri raamiga, kus oli üks pikk tugitala, kuhu kinnitusid ülejäänud detailid. Kui raam oli läbi mõeldud ja projekteeritud, pidi sellele tegema ka tugevusanalüüsi, et kindlustada raami vastupidavus koormusele ja väändele. Sama tuli teha ka õõtshoova ja käändmikuga. Nagu raamiga, tuli eelnevalt uurida, kuidas olid projekteeritud sarnaste sõidukite detailid ja teha nendest analüüs. Läbi tuli ka mõelda, kuhu ja kuidas omavahel kõik detailid kinnituvad. V-kujulised õõtshoovad kinnitusid raami külge kahe puksiga ja ühe amordiga. Käändmik, mis autor projekteeris karbi kujuga, kinnitus õõtshoova külge M12 poldiga, käändmik liikus õõtsa ümber radiaallaagrite abil. Sarnaselt oli vaja teha tugevusanalüüs ka nendele komponentidele ja dimensioneerida need piisava varuteguriga. Veel oli vaja valida välja sobilikud vedrud ja amordid, mis teeks sõitmise juhile mugavaks, kuid samas oleks piisavalt jäigad. Selleks pidi autor arvutama ülekandeteguri ja leidma raskuskeskme ning nende abil arvutama vajalikud vedru jäikused. Sõiduki pidurdamiseks pidi autor välja arvutama vajaliku jõu ning projekteerima piduri suporti kronsteini, mis peaks pidurdamisel tulevale momendile vastu. Lisaks oli vaja autoril lahendada ka projekteeritava sõiduki juhtimine ja juhi ergonoomika. Juhtimine sai tehtud lihtne ja robustne. Roolimine käis läbi lenksu, mis ühendus toruga., toru alla keevitub plaat, kuhu kinnituvad rooliotsa munakat. Teised munaka otsad kinnituvad käändmiku küljes olevate kõrvade külge. Lenksu projekteeris autor reguleeritavaks üles-alla ja kahes erinevas punktis lenksu pikenduse küljes kallet muutvaks. Samuti oli reguleeritav ka iste mitmes suunas, mis tuli teise invaskuutri pealt. Mootorite valikuks said 350W rummumootorid , igale rattale oma. Mootorid tulid komplektina, kus oli lisaks kahele mootorile koos rehviga ka kaks kontrollerit, kaks piduriketast ja suporti, LCD ekraan ning drossel käepide. Veel oli vaja välja arvutada kui suure mahutuvusega akusid oli vaja sõidukile, et baasandmetes paika pandud teekonda läbida ning valida välja akud koos muude voolutarbijatega. Viimaks oli veel vaja teha maksumuse analüüs ja lüüa kulude numbrid kokku. Lõputöös eesmärgiks pandud 2000 euro suuruse summaga antud masinat projekteerida ei saaks kuid sellegipoolest autor arvab, et käesolevat sõidukit tuleks edasi arendada kuna Eesti turul sarnast sõidukit sihtgrupile ei ole, analoogse masina saaks vaid välismaalt tellides suure raha summa eest.

In the thesis, the author set his goal to design a off-road capable mobility scooter frame with control arms and knuckles and also to choose the components that are needed to complete them. To do so, the author had to firstly find out what kind of laws and under what category Rebublic of Estonia had set on for the vehicle that the author wanted to design. Furthermore an analysis was done on five different analogous mobility scooters to understand what are the benefits that make them good on off-road, what make them difficult to design and how comfortable and easy it is to use for the targeted group. Author of the thesis also went to learn more and drive a similar scooter to understand better how to design his own project. Also as author is not in the targeted group he made a survey for 20 people who were elderly or handicaped. From the survey he found out out what were the expectations and wishes for the people whom a similar vehicle would be practically indispensable. Designing started with laying out the base data such as scooters dimensions, clirens, driving range and selecting drivetrain. Also calculating the needed power to move the scooter. For the next the author had to choose the material for the frame, control arms and knuckle. There was a choice between aluminium and steel, author chose steel because it was cheaper and easier to work with. The last feature was very important because the author wanted to build the scooter at home conditions. Material chosen, it was time to start designing. Frame was the first thing the author started with. Frame was made similar with the frame of scooter seen from the visit. Frame was made from a one long support beam where all other details things attached to. When the frame was designed, author also had to do a strenght analysis to insure the frame held up to loads and moments coming from the road. Same process was done with control arm and knuckle. As with frame, before designing author researched how those components were designed on other similar vehicles and analysed them. Author also had to think through how all and where the components attached to. V shaped control arms attached to the frame by two bushings and with one shock. Knuckle was desinged as a boxed shape, it was attached to the control arm with a M12 polt. Knuckle pivoted around the control arm with a couple of radial bearings. Like with frame a strenght analysis had to be done for these components to assure they had propper factor of safety. In addition author had to choose right springs and shocks that would make the driving for comfortable. For that the author had to calculate the motion ratio and find the vehicles center of gravity. He used that data to calculate the needed spring stiffnesses. To stop the vehicle author had to calculate the needed force and design a brake suport bracket that had to withstand the torque coming from braking. Further more the author had to solve the steering of the designed vehicle and ergonomics. Steering was designed to be easy and sturdy. Steering was done with handlebars that was connected to a pipe. Plate, welded under the pipe, attached two tie rod ends. Two other ends of the tie rods were attached to ears on knuckles. Handlebars was designed to move up and down and to change angle from to different points on the stem. Seat that came from a different mobility scooter was also adjustable in several directions. Motors chosen were 350 W hubmotors, each wheel their own motor. The two motors came in a kit along with two controllers, two brake discs, two brake calipers, one LCD screen and one throttle grip. Also author had to calculate the capacity and choose the batteries needed to traverse the distance author had set in the base data. Author also had to include other electric consumers that the vehicle had. Lastly author had to do a cost analysis and round up the numbers. Goal 2000 euros set at the start of the thesis was not enough money to design the vehicle as it was but nonetheless author thought that the vehicle should be designed further because there was not a similar scooter sold in Rebublic of Estonia unless it was orded from other country for a hefty price.