Smjernice za usporedbu i procjenu elemenata motora s unutarnjim izgaranjem u svrhu poboljšanja buke i vibracija

master's thesis

• Title (english): Guidelines and benchmarking of the internal combustion engine components for enhacement of NVH performance
• Author: Valentina Vizir
• Mentor: Darko Kozarac (mentor)
• Granter: University of Zagreb; Faculty of Mechanical Engineering and Naval Architecture; Zagreb
• Defense date and country: 2019-05-17, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Mechanical Engineering

Abstract

Osim manje potrošnje goriva i velike snage, udobnost u vožnji vrlo je važan zahtjev kod kupnje vozila. Budući da je motor s unutarnjim izgaranjem jedan od glavnih izvora buke i vibracija u vozilima, analiza buke i vibracija predstavlja velik izazov u razvoju motora s unutarnjim izgaranjem.
Cilj ovog rada je odrediti odgovarajuću metodu koja bi omogućila predviđanje vibracija pojedinih komponenata motora s unutarnjim izgaranjem na početku razvoja prije nego što je poznata konstrukcija cijelog motora. Time bi se smanjili troškovi i vrijeme potrebno za razvoj motora s unutarnjim izgaranjem.
Analizirana su tri prednabijena redna trocilindarska Otto motora. Pojedini dijelovi motora (usisna grana, uljno korito i poklopac glave motora) analizirani su u trećinsko-oktavnom pojasu od 800 Hz do 3150 Hz (frekvencijsko područje od 708 Hz do 3548 Hz). Prvo je potrebno definirati odgovarajuće rubne uvjete koji bi zamijenili utjecaj opterećenja koje se prenosi iz bloka motora preko vijčanog spoja na određenu komponentu motora. Rubni uvjeti su definirani u obliku ubrzanja. Nakon toga, različiti tipovi krivulja ubrzanja primjenjuju se u čvorovima na mjestima vijčanog spoja promatrane komponente s ostatkom strukture. Na kraju, rezultati su uspoređeni na temelju raspodjele vibracija po površini strukture i ovisno o tome koliko pojedina komponenta pridonosi ukupnim vibracijama motora s unutarnjim izgaranjem.

Abstract (english)

Lower fuel consumption and high power, together with the increased driving comfort, represent some of the most important customer demands. Since internal combustion engine represents one of the biggest contributors to the overall noise and vibration levels, a special attention should be given to the NVH (noise, vibration, harshness) analysis. The objective of this study is to define a method for predicting the NVH performance of the engine components at early stages of engine development before they are coupled to the full engine assembly. As a result, the whole development process would be less time and money consuming.
The study is conducted for three gasoline turbocharged inline 3-cylinder engines. Engine components (intake manifold, oil pan and cam cover) are analyzed in mid and high frequency domain for 3rd octave band 800 Hz up to 3rd octave band 3150 Hz (from 708 Hz to 3548 Hz). The first step is to define the adequate boundary conditions that will replace the impact of the forces generated in the engine block and transmitted through the bolts to the observed component. Boundary conditions are defined in the form of enforced motions (accelerations). After that, different types of acceleration curves are applied as excitations at the bolt locations in the forced frequency response analysis. Finally, structure response is evaluated in 3rd octave bands based on the distribution of the surface velocities and the contribution of the observed component to the overall noise radiation level.

• Keywords: NVH; excitation; engine; response; acceleration
• Keywords (english): Buka; vibracije; uzbuda; odziv; ubrzanje
• Language: english
• URN:NBN: urn:nbn:hr:235:941622
• Study programme: Title: Mechanical Engineering; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra inženjer/inženjerka strojarstva (magistar/magistra inženjer/inženjerka strojarstva)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2019-05-23 00:47:22