|
|
Crank mechanism with a high mechanical efficiency
Drápal, Lubomír ; Tůma, Jiří (referee) ; Páv,, Karel (referee) ; Píštěk, Václav (advisor)
This document describes the possibilities of increasing the mechanical efficiency of the crank train of an internal-combustion engine. For this purpose, a concept with a reduced number of main bearings is chosen and its contribution is verified experimentally. The proposed solution consists of an innovative crankshaft design of a four-cylinder spark-ignition engine with only three main journal bearings and laser-welded sheet metal crank webs. The new design is compared to the mass-produced one in terms of friction losses, vibrations and loading of engine parts by means of simulations of crank train dynamics using the Multi-Body System. The increase in vibration, accompanied by a reduction in friction losses, is compensated by a torsional vibration damper and its effect is experimentally verified. Experimental research of laser welds on the crankshaft in terms of fatigue life is also described. The overall potential is also summarised and further possible development of this innovative and patented design is outlined.
|
|
|
Vibration and Acoustic Emission Reduction of Powertrains using Virtual Engine
Svída, David ; Kovář, Rudolf (referee) ; Dundálek, Radim (referee) ; Kovář, Rudolf (referee) ; Dundálek, Radim (referee) ; Píštěk, Václav (advisor)
Doctoral thesis deals with combustion engine cranktrain vibrations and vibration analysis methods. The work applies new computational models aimed at powertrain vibration decrease. The computational models can be used in the first stages of powertrain development. Temperature dependences of the rubber shear modulus and loss factor characteristic are found by response analysis of the free damped vibrations in the first part of the thesis. Viscoelastic model parameters of two dampers with different rubber hardness are calculated using optimization methods. Temperature distribution inside the rubber part during the harmonic oscillation is calculated with the knowledge of previous values. Computational models together with a user interface are assembled in Matlab/Simulink software tool. Computational model results of the viscoelastic rubber damper are verified by measurements on a prototype diesel engine in the whole operating engine speed range. Torsional vibrations of the crankshaft with torsional damper are measured by POLYTEC laser rotational tools. The temperature distribution on the damper surface is obtained by Infratec VarioCAM thermographic system. Combustion pressures in the cylinder are measured by SMETEC Combi indication tools. Both the temperature distributions and combustion pressures are used for computational purposes. All the measurement procedures are described also in the thesis.
|
|
|
Introduction of loadcase „Creeping“ to a multi-body simulation
Volek, Matěj ; Lošák, Petr (referee) ; Březina, Lukáš (advisor)
Tato diplomová práce je zaměřena na implementaci procesu simulace zatěžovacího zatížení do stávajícího rozhraní používaného pro multi-body simulace hnacího vozidla. „Creeping“ bylo definováno jako řízení vozidla bez nárazu na plynový pedál v nízkých převodech. Bylo rozhodnuto simulovat tento stav zavedením sil Jízdních odporů – Aerodynamická odporová síla Fa, síla Valivého odporu Fr a horizontální část Gravitační síly Fgx. Tyto síly byly modelovány v softwaru SimulationX a byl definován model pro zatížení „Creeping“ – ten byl založen na změně stoupání kopce, což dalo výsledky potřebné pro analýzu chování při stavu „Creeping“. Poté byly vytvořeny soubory v softwaru Matlab potřebné pro běh a následné zpracování simulace, které analyzují výsledky v závislosti na čase nebo průměrném točivém momentu motoru. Potom byla správnost procesu kontrolována ve srovnání s experimentálními daty. Toto srovnání ukázalo, že proces pracuje bez velkých problémů; výsledky vykazovaly podobný trend, byly ale ovlivněny nedostatkem vstupních dat z experimentu.
|
|
|
Five-cylinder diesel engine for commercial vehicles
Švarc, Marek ; Kučera, Pavel (referee) ; Píštěk, Václav (advisor)
The aim of this diploma thesis is the design of the configuration and the method of balancing the crank mechanism with the specified parameters. For a particular configuration, a crankshaft drawing is processed and a strength analysis, considering the crankshaft torsional vibrations is performed in Ansys FEM software. At the end of the thesis, an ideological design of the torsional vibration damper and its effect on the crankshaft stress in the Ansys FEM software is performed.
|
|
|
Crank mechanism with a high mechanical efficiency
Drápal, Lubomír ; Tůma, Jiří (referee) ; Páv,, Karel (referee) ; Píštěk, Václav (advisor)
This document describes the possibilities of increasing the mechanical efficiency of the crank train of an internal-combustion engine. For this purpose, a concept with a reduced number of main bearings is chosen and its contribution is verified experimentally. The proposed solution consists of an innovative crankshaft design of a four-cylinder spark-ignition engine with only three main journal bearings and laser-welded sheet metal crank webs. The new design is compared to the mass-produced one in terms of friction losses, vibrations and loading of engine parts by means of simulations of crank train dynamics using the Multi-Body System. The increase in vibration, accompanied by a reduction in friction losses, is compensated by a torsional vibration damper and its effect is experimentally verified. Experimental research of laser welds on the crankshaft in terms of fatigue life is also described. The overall potential is also summarised and further possible development of this innovative and patented design is outlined.
|
|
|
Introduction of loadcase „Creeping“ to a multi-body simulation
Volek, Matěj ; Lošák, Petr (referee) ; Březina, Lukáš (advisor)
Tato diplomová práce je zaměřena na implementaci procesu simulace zatěžovacího zatížení do stávajícího rozhraní používaného pro multi-body simulace hnacího vozidla. „Creeping“ bylo definováno jako řízení vozidla bez nárazu na plynový pedál v nízkých převodech. Bylo rozhodnuto simulovat tento stav zavedením sil Jízdních odporů – Aerodynamická odporová síla Fa, síla Valivého odporu Fr a horizontální část Gravitační síly Fgx. Tyto síly byly modelovány v softwaru SimulationX a byl definován model pro zatížení „Creeping“ – ten byl založen na změně stoupání kopce, což dalo výsledky potřebné pro analýzu chování při stavu „Creeping“. Poté byly vytvořeny soubory v softwaru Matlab potřebné pro běh a následné zpracování simulace, které analyzují výsledky v závislosti na čase nebo průměrném točivém momentu motoru. Potom byla správnost procesu kontrolována ve srovnání s experimentálními daty. Toto srovnání ukázalo, že proces pracuje bez velkých problémů; výsledky vykazovaly podobný trend, byly ale ovlivněny nedostatkem vstupních dat z experimentu.
|
|
|
Five-cylinder diesel engine for commercial vehicles
Švarc, Marek ; Kučera, Pavel (referee) ; Píštěk, Václav (advisor)
The aim of this diploma thesis is the design of the configuration and the method of balancing the crank mechanism with the specified parameters. For a particular configuration, a crankshaft drawing is processed and a strength analysis, considering the crankshaft torsional vibrations is performed in Ansys FEM software. At the end of the thesis, an ideological design of the torsional vibration damper and its effect on the crankshaft stress in the Ansys FEM software is performed.
|
|
|
Vibration and Acoustic Emission Reduction of Powertrains using Virtual Engine
Svída, David ; Kovář, Rudolf (referee) ; Dundálek, Radim (referee) ; Kovář, Rudolf (referee) ; Dundálek, Radim (referee) ; Píštěk, Václav (advisor)
Doctoral thesis deals with combustion engine cranktrain vibrations and vibration analysis methods. The work applies new computational models aimed at powertrain vibration decrease. The computational models can be used in the first stages of powertrain development. Temperature dependences of the rubber shear modulus and loss factor characteristic are found by response analysis of the free damped vibrations in the first part of the thesis. Viscoelastic model parameters of two dampers with different rubber hardness are calculated using optimization methods. Temperature distribution inside the rubber part during the harmonic oscillation is calculated with the knowledge of previous values. Computational models together with a user interface are assembled in Matlab/Simulink software tool. Computational model results of the viscoelastic rubber damper are verified by measurements on a prototype diesel engine in the whole operating engine speed range. Torsional vibrations of the crankshaft with torsional damper are measured by POLYTEC laser rotational tools. The temperature distribution on the damper surface is obtained by Infratec VarioCAM thermographic system. Combustion pressures in the cylinder are measured by SMETEC Combi indication tools. Both the temperature distributions and combustion pressures are used for computational purposes. All the measurement procedures are described also in the thesis.
|
guest ::
