L6e kategooria linnaauto roolisüsteemi projekteerimine

Töö käigus püstitatud ülesanded on leidnud lahenduse. Kompromissi korras on valitud hambumise parameetrid ning teostatud arvutus. Linnaauto pöördediameeteriks on saavutatud klassi parim 6,8m, ühtides konkurendiga Renault Twizy või Smart Fortwo ning rooligeomeetriaga sai saavutatud hea manööverdavus. Vastuse leidis ka küsimus, kas linnaautot on võimalik parkida ühele parkimiskohale mitu. Olenevalt parklast ning parkimisviisist on neid võimalik ühele kohale mitu tükki parkida. Töö teises pooles sai välja pakutud roolilati lahendus, mis autori arvates toimib. Hambumise valikul osutus hammasratta ülekande varutegur 2,5 piisavaks. Palju vaeva tuli näha roolilati koostu kallal, sest esines palju nüansse nii materjali, laagrite ja tihendite valiku osas ning täpsemalt läbi mõelda detaili valmistamine ja koostamine. Projekteeritud detailide maksumuseks kujunes 795 eurot. Roolisüsteemi paigutuse jaoks valmistatud ning kasutatud detailid on asetatud mudelsõidukisse. Mannekeeni lisamisega juhiistmele sai selgeks, et roolisüsteemi paigutamine ei olegi nii kerge kui algul paistab, ruumi on vähe ning iga liigutus toob kaasa kogu süsteemi sobivuse ümber hindamise. Autor hindas kolme erineva paigutuse sobivust ning selle põhjal on tehtud valik ja soovitus. Töö kolmandas pooles on hinnatud sisendvõlli ja hammaslati käigupiiraja tugevust, muutes materjali ning geomeetriat, on saavutatud varutegurid 3,6 ja 4,4 piisavad. Autori poolset projektilahendust tuleks prototüübil katsetada ning veenduda et roolisüsteem toimib nagu peab. Vajadusel tuleks projekteerida ka hambumise reguleerimise võimalus. Sõiduki teljevahe tuleks vähemalt 65mm ulatuses tõsta ning tuleks kaaluda ka pöördalusel istme kasutusele võtmist täiendava juhi sisenemismugavuse tõstmiseks.

The thesis topic of Design of the Steering System for the L6e City Car is relevant because this is an actual project which is currently in planning. The main objective of this thesis is to design a working steering rack solution. Additional objectives include how to ensure the best maneuverabilty, turning diameter, how is it possibe to park the city car and whether it’s possible to park multiple cars on one parking spot. To solve these objectives multiple targets were set: choosing gearing parameters and calculation, analysis of maneuverabilty and turning radius. Work also had to be done on designing the models: firstly the model of the steering rack, then the steering rack assembly and the last big task of fitting the entire steering system to the model car. The set objectives have been accomplished and solutions found. Gearing parameters were chosen and calculations were conducted. Comparing to Renault Twizy and Smart Fortwo, best turning diameter of 6,8m was achieved. Dependant of the parking arrangement and the way the car is parked, it is possible to park multiple city cars on one parking spot. Factor of safety of 2,5 was sufficient for the gearing. A lot of labour went into designing the steering rack assembly because many variables had to be considered during the choice of materials, bearings and seals. Cost of designed elements is 795 euro. All the fabricated parts were placed into the model vehicle, which turned out to be very challenging. A lack of room was always present when trying to find an appropriate location for the steering system. Author considered three different solutions and the best was chosen. During the analysis of the material, strength of the input shaft and the steering rack limiter were evaluated. After changing the material and its geometry, adequate factor of safety of 3,6 and 4,4 were achieved. The designed solution by the author should be tested on the prototype to assure that the steering system works as it should. If necessary adjustabilty of the gear mesh should be designed. Additionally the wheelbase of the vehicle should be increased by 65mm and swivel seat should be considered as a supplementary feature to ease the entry into the vehicle.