National Repository of Grey Literature 49 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
Cranktrain with High Mechanical Efficiency
Krajči, Jakub ; Raffai, Peter (referee) ; Novotný, Pavel (advisor)
This master's thesis is concerned with the mechanical efficiency of cranktrain contact pairs in a combustion engine. In the introductory part, the fundamental terminology relating to the cranktrain is presented along with the specification of the areas of mechanical losses, greasing modes and types of wear. The following chapters describe the possibilities of eliminating mechanical losses of the cranktrain and the calculation methods that can be utilized to mathematically solve mechanical losses. The practical part includes the proposal of a calculation model and its use in the analysis of the cranktrain of Skoda 1.2 HTP engine. The last part of this thesis comprises modified alternatives of the standard cranktrain focusing on the elimination of mechanical losses. The evaluation of the results is presented in the conclusion of this thesis.
Computational Tool for Gas Flow Modeling through the Piston Assembly
Vitteková, Zuzana ; Dlugoš, Jozef (referee) ; Raffai, Peter (advisor)
The main topic of this bachelor’s thesis is to create a graphical users interface (GUI) in Matlab, facilitating the entry of input parameters for the calculation of the gas flow through the piston assembly and its evaluation. The first part is dedicated to the theory of piston rings followed by an introduction into the gas flow problematics. The second part concerns the procedure of creating the aforementioned GUI.
Surface treatments of internal combustion engines cylinders
Malec, Petr ; Raffai, Peter (referee) ; Maršálek, Ondřej (advisor)
This bachelor thesis is a professional research, which describes the most common methods of surface treatments of modern internal combustion engines cylinders. The work consists of the distribution of the species changes, their use and justification of their application. It also describes the technology of individual surfaces, their coating and finishing operations to achieve the best results of sliding surface.
Modeling the Impact of Piston Rings on Oil Consumption of Internal Combustion Engines
Raffai, Peter ; Pavlov,, Michal (referee) ; Dr. Dan E. Richardson (referee) ; Kučera, Pavel (referee) ; Novotný, Pavel (advisor)
V rámci této práce byl vyvinut komplexní simulační nástroj, vycházející z výpočtového modelování fyzikálních a chemických dějů, který je doplněn vhodnými matematickými postupy. Výsledný software je schopen stanovit ztrátový výkon sady pístních kroužků pomocí účinků klíčových mechanismů a jejich vzájemné interakce při standardním provozu pístních kroužků. Simulační výstupy byly navrženy v souladu se zájmy průmyslové praxe, např. určení objemového toku plynů pístní skupinou, ztrátové výkony vlivem tření a spotřeba oleje, která je ovlivněna sadou pístních kroužků. Při vývoji simulačního modelu byly technické experimenty vykonány na tříválcovém zážehovém motoru za účelem získání vstupních dat a ověření výsledků. Možnosti navrženého simulačního nástroje jsou na tomto motoru dále demonstrovány v podobě parametrických studií, využitelných zejména při návrhovém procesu. Cílem dizertační práce bylo zaplnit mezeru ve výzkumné oblasti simulačních nástrojů, které mohou účinně propojit výpočtové modelování třecích ztrát a současně i spotřeby oleje, a podpořit tak výrobce pístních kroužků a vývojová oddělení spalovacích motorů.
Reduction of Contact Pairs Friction Losses
Novotný, Marek ; Raffai, Peter (referee) ; Maršálek, Ondřej (advisor)
This bachelor thesis deals with the topic of mechanical efficiency of contact pairs in the crankshaft of the combustion engine. The introductory section focuses on the efficiency of the combustion engine as a whole. In addition, it describes the areas where mechanical losses primarily occur. The following chapters describe mechanism of friction losses, the main factors affecting their amount and the most modern ways to increase mechanical efficiency. In the closing chapter, some basic computing relations, describing the size of mechanical losses are listed. The aim of this thesis is to acquaint the reader with the importance of mechanical efficiency in the area of combustion engines.
Modern Trends in Vehicle Front Lights Design
Rada, Jakub ; Maršálek, Ondřej (referee) ; Raffai, Peter (advisor)
This bachelor’s thesis deals with the modern trends in the design of the headlamps. The first part presents the sequential stages of development of systems used for headlamps and their design solutions. The second part focuses on the possible cooling alternatives of functional parts in lighting modules, completed with the results of comparative laboratory tests performed by front manufacturers of automotive lighting. The final section contains a comparison of the currently most widely used technologies in the vehicle front lighting.
Sport cars BMW - from history to present
Raffai, Peter ; Svída, David (referee) ; Dundálek, Radim (advisor)
Bachelor’s thesis incorporates vehicles of the Bayern Motor Works, which managed to become an everlasting icon among sports cars, and also recent models, which are determined to keep this tradition alive. Presented are some interesting technical innovations of division Motorsport GmbH and their evolution until present.
Car Door Handle FEM Model Creation and Validation for Crash Simulations
Raffai, Peter ; Korouš, Jan (referee) ; Ramík, Pavel (advisor)
The aim of this master’s thesis was to create a component model of a door handle stiffener used by the Volkswagen concern, which can be used for crash computations. Also to tune its parameters the way, its behavior corresponds the most to the real part’s. In the theoretical part the current regulations of the Euro NCAP are presented, concerning the testing and evaluation of the passive safety of new vehicles. Attention is focused on the evaluation of the side impact barrier tests, where the effect of the door handle stiffener’s damage is reflected the most. Shown are the reasons for the effort to simulate the real behavior of the stiffener, the factors, which initialized the born of the studied problem. The practical part starts with the creation of the FEM mesh of the part based on its 3D CAD model, also describes the requirements for the mesh quality, as well as the used tools and methods. Further on investigated are the characters of real damages of the door handle area during side impacts, based on which the component tests are proposed for the validation of the simulation model. Experimental research consists of the stiffener’s testing for simple bend and twist loads, three specimens each. After the execution of the tests the results get compared with the corresponding simulations. Modifications are made on the model according to the acquired results: refinement of the FEM mesh, new material model usage with failure for shell elements and definition of real material characteristics for the used thermoplastics. The latest obtained simulation dependencies are compared with the measured values again, the results are evaluated at last.
Thermal-Mechanical Analysis of the Cylinder of the Four-stroke Engine
Ptáček, Petr ; Raffai, Peter (referee) ; Dlugoš, Jozef (advisor)
This diploma thesis is focused on creating a finite element method model of a four-stroke engine with a purpose to determine an impact on cylinder bore distortion caused by several types of loading. Introduction of this work covers research of possibilities in modelling thermal-structural analysis of cylinder liner and verifications of the analysis results. An Ansys model was further created and cylinder liner radial deformation caused by head bolts tightening and thermal loading coming from combustion was determined. Finally, a whole engine working cycle was simulated with a gas pressure loading and its final impact on the total cylinder liner radial deformation was defined.
Vehicle Safety Assist Systems and Their Assessment under Euro NCAP Directives
Szabó, Ákos ; Zubík, Martin (referee) ; Raffai, Peter (advisor)
The aim of this bachelor’s thesis was to create overview about vehicle safety assist systems and to show their impact of road traffic safety. In the first part of this thesis systems were categorized by their function and characteristic.After that there were created a survey about accident rate and there were shown the most common causes in road accidents. In the second part was discussed principle how brake assist systems and automatic emergency braking work. In the last section was explained assessment under Euro NCAP directives, where the attention was focused onassesment of the experimentsof safety assist.

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