Numerička analiza rada sustava Valvetronic

Pakšec, Dora (2018) Numerička analiza rada sustava Valvetronic. = Numerical analysis of Valvetronic system operation. Undergraduate thesis , Sveučilište u Zagrebu, Fakultet strojarstva i brodogradnje, UNSPECIFIED. Mentor: Kozarac, Darko.

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Abstract (Croatian)

Kako bi se ostvarile bolje performanse automobila proizvođačima se nameću novi tehnološki izazovi. S obzirom na današnju ekološku osviještenost i sve više prisutan efekt staklenika, motorima s unutarašnjim izgaranjem postavljaju se sve veći zahtjevi u pogledu emisija štetnih produkata izgaranja i potrošnje goriva. Potpuno varijabilni ventilski razvod prepoznat je kao jedna od tehnologija koje najviše obećavaju, posebno zbog prednosti u smanjenju potrošnje goriva i povećanju zakretnog momenta motora pri nižim brzinama vrtnje uz smanjenje štetnih emisija. Predmet ovog završnog rada je utjecaj sustava Valvetronic na rad Ottovog četverotaktnog, četverocilindarskog, rednog, automobilskog motora. Korištenjem AVL-ovog programskog paketa "Boost" biti će uspoređena dva motora. Radi se o BMW-ovom motoru N46B20 koji ima ugrađen sustav Valvetronic. Jedan motor će biti simuliran sa zaklopkom a drugi sa sustavom Valvetronic kako bi se mogli usporediti parametri motora i vidjeti koje parametre poboljšava Valvetronic sustav. Motor s Valvetronic sustavom ne koristi zaklopku za regulaciju snage već omogućuje beskonačno promijenjivo podizanje usisnog ventila i time je u stanju smanjiti potrošnju gotiva i do 10% te ujedno smanjiti emisije. Kod klasičnog motora sa zaklopkom pritiskom papučice gasa povećavamo količinu zraka koji ulazi u cilindre. Sustav za ubrizgavanje goriva nadzire količinu zraka koja prolazi kroz zaklopku i zatim određuje potrebnu količinu goriva. Međutim pri slabo otvorenoj zaklopci kada je automobil npr. pod djelomičnim opterećenjem ili vozi nizbrdo, zaklopka se djelomično ili čak gotovo zatvara. Istodobno se klipovi još uvijek pokreću, usisavajući zrak iz djelomično zatvorenog usisnog razvodnika. Time će se između zaklopke i komore za izgaranje stvoriti djelomični vakuum i doći će do otežanog usisavanja u taktu usisa. To predstavlja gubitke pumpanja. Dakle, što je zaklopka zatvorenija gubi se više energije. Upravo to je jedan od razloga zašto se počela koristiti regulacija ventilima a ne zaklopkom. Simulacije su pokazale da motor sa sustavom Valvetronic ima brojne prednosti od kojih se najviše ističe manji gubitak pumpanja odnosno smanjena potrošnja goriva te smanjene emisije. Također, Valvetronic smanjuje troškove održavanja, poboljšava hladno pokretanje motora i omogućuje glađi rad motora, a zbog finog raspršivanja goriva ne zahtijeva posebnu vrstu ili kvalitetu goriva.

Abstract

In order to improve car performance, manufacturers are continually challenged to develop new technologies. Given today's environmental awareness and the ever-increasing greenhouse effect, very strict requirements have been imposed on internal combustion engines regarding combustion emissions and fuel consumption. Fully variable valve timing is recognized as one of the most promising technologies, especially in view of reducing fuel consumption and increasing torque at low speeds while cuttingharmful emissions. The aim of this thesis was to study the impact of the Valvetronic system on the operation of the Otto four-stroke, four-cylinder, inline, automobile engine. Using the AVL Boost software package, two different versions of the BMW N46B20 engine, a throttled engine and an engine with a Valvetronic system, were compared. To compare engine parametres and find out which parametres get improved when using the Valvetronic system, a throttled engine and a Valvetronic engine were simulated. The Valvetronic engine does not use throttle to regulate power, but it allows for an infinitely variable intake valve lift, reducing fuel consumption by up to 10% and cutting emissions at the same time. In a conventional throttled engine, by pressing the gas pedal the amount of air entering the cylinder gets. The fuel injection system controls the amount of air that passes through the throttle and saves the required amount of fuel. However, at light throttle, when the car is under partial load or drives downhill, the throttle butterfly is partially or almost completely closed. At the same time, the pistons are still running, taking air from the partially closed intake manifold. This creates a partial vacuum between the throttle and combustion chambers and results in difficult suction upon the intake stroke. This presents a waste of pumping. So, the more closed the throttle is, the more energy is lost. That is one of the reasons why regulating the valves instead of the throttle started to be used. Simulations have shown that the Valvetronic engine has many advantages, such as reducing pumping losses, fuel consumption and emissions. Also, the Valvetronic system reduces maintenance costs, improves the cold start of the engine and allows the engine to run smoothly. Finally because of its fine fuel atomization, it does not require a specific type or fuel quality.

Item Type: Thesis (Undergraduate thesis)
Uncontrolled Keywords: Valvetronic, ventili, zaklopka, potrošnja, emisije
Keywords (Croatian): Valvetronic, valves, throttle, fuel consumption, emissions
Subjects: TECHNICAL SCIENCE > Mechanical Engineering
Divisions: 400 Department of IC Engines and Mechanical Handling Equipment > 410 Chair of IC Engines and Motor Vehicles
Date Deposited: 26 Sep 2018 09:51
Last Modified: 29 Nov 2019 14:48
URI: http://repozitorij.fsb.hr/id/eprint/8830

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