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The influence of the frequency converter on the life and damage of bearings
Sukovatý, Adam ; Krejčí, Petr (referee) ; Nahodil, Petr (advisor)
This thesis deals with the effect of frequency inverter on the lifetime of roller bearings. The measurement has been carried out on the frequency inverter and induction motor by Siemens in the Switchgear laboratory of Fakulty of elektrical engineering and communication. Data has been recorded and processed on Adash VA4 Pro analyzer. Methods of measuring RMS values and frequency analysis of vibration and current were used for the analysis. Based on the mutual similarity of frequency spectrum, the presence of the high frequency capacitive current in the bearings has been proven. To prevent this, possible solutions have been presented. In the second part of the experiment an effect of changing pulse width modulation (PWM) on vibration was examined. The goal was to make a basic analysis and to provide background material for further research.
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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.
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Power Losses of a Rolling Bearing
Šedo, Matej ; Novotný, Pavel (referee) ; Drápal, Lubomír (advisor)
Subject of this thesis is analysis of friction power losses in rolling bearings and design and implementation of computing program. Thesis is divided into six chapters. At the beginning there is overview of different types of rolling bearings and their system of lubrication. Fundamentals of elastohydrodynamic lubrication are described together with effects that occur in lubricant. Remaining part is focused on friction in rolling bearing its sources and calculation. Other programs for computing friction losses are shown and own program is designed. Designed program is applied on bearings of chosen type and results are compared with existing models.
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Diagnosis of mechanical vibrations in asynchronous motor origin
Dostál, Martin ; Dostál, Lukáš (referee) ; Janda, Marcel (advisor)
Every machine needs to be maintained and controlled, if may work reliably during they service life. Big part of service life of expensive machines are those machines in operation. Vibration diagnostics is type of analysis, that doesn’t need removal of rotation machinery. The vibration, that are created by running machinery, are used as source of information about mode of operation. This master’s thesis contains theoretical analysis of vibration diagnostics and vibration measurements of a particular machine. This thesis contains 3D models of bearings and rotor asynchronous machine, which are created by software Autodesk Inventor 2014. Bearings vibration analysis of this models is performed by software Ansys Workbench.
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