Continuously variable transmission

U radu je navedena povijest razvoja CVT-a te su opisani najznačajniji sustavi koji omogućavaju automatsku promjenu prijenosnog omjera. Opisan je njihov princip rada, a kao jedan njihov predstavnik izdvojen je CVT. Navedene su vrste CVT-a te je detaljno opisan princip rada hidrauličkog CVT-a sa svim njegovim specifičnim dijelovima i komponentama. Za dobivanje boljeg uvida u rad prijenosnika s kontinuiranom promjenom prijenosnog omjera, proveden je proračun usporedbe ubrzanja automobila snage 105 kW do brzine od 100 km/h s ručnim mjenjačem i s CVT-om. Također, proveden je proračun dimenzioniranja CVT-a za automobil snage 75 kW na temelju kojeg se provelo modeliranje sustava u softwareu Autodesk Inventor 2019. Pri izradi modela posebnu pažnju trebalo je posvetiti konstrukciji i principu rada hidrauličkog dijela. Na osnovu zahtjeva koje je potrebno zadovoljiti kako bi hidraulički sklop mogao funkcionirati, izvelo se konstrukcijsko rješenje s posebno oblikovanim načinom spajanja hidrauličnog klipa i pomične remenice. Također je bilo potrebno pravilno osmisliti uležištenje cjelokupnog sustava kao i izraditi posebno oblikovano kućište kako bi sustav zauzimao što manje mjesta. U konačnici su izrađeni radionički crteži svih bitnih dijelova u sustavu, sklopni crteži s BOM sastavnicom, te raščlanjeni prikaz sustava s BOM sastavnicom.This paper describes history of CVT development and the most significant systems that allow automatic transmission gear ratio change. Furthermore, paper describes working principle of automatic transmission system and takes CVT as an example of such system. Different CVT types are specified and working principle of hydraulic CVT is described in detail with its specific parts and components. In order to provide better insight into the performance of gearbox with continuous gear shift ratio, a comparison of acceleration from 0 km/h to 100 km/h was performed, comparing a car with 105 kW motor with manual gearbox and CVT. Also, modeling calculation of CVT dimensioning was performed for a car with 75 kW which was used as a base for system modeling using Autodesk Inventor 2019 software. When designing the model, special attention was given to the construction and working principle of the hydraulic part. Based on the requirements that needs to be met in order to hydraulic circuit to function, a construction solution with a specially shaped connection between hydraulic piston and mobile pulley was performed. It was also necessary to properly design the system bearing as well as to create a specially designed housing to make the system as small as possible. Finally, work drafts of all essential system parts were made, along with circuit drawings with the BOM component, and exploded view with the BOM component