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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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Bearings for space
Vavřík, Petr ; Nečas, David (referee) ; Košťál, David (advisor)
Currently, space satellites in orbit are required to operate reliably for more than 10 years. This places high demands on the satellite's tribological systems, which must function properly in the hostile space environment for this period. This bachelor thesis deals with the description of suitable bearings and their lubrication for space applications. Lubrication regimes are described at the outset. Then, space factors affecting the proper operation of tribological systems are summarized. The largest part is devoted to the description of the most used bearings and lubricants. The thesis concludes with the design of suitable bearings and their lubrication for the satellite reaction wheel.
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Design of apparatus for testing of bearings
Sovadina, František ; Šperka, Petr (referee) ; Svoboda, Petr (advisor)
In this bachelor thesis an analysis of used test devices for durability of the rolling bearing was performed. This analysis then serves as an inspiration for the reconstruction of the existing bearing test facility at FME BUT. Three conceptual designs have been developed and, after consideration of all aspects, drawing documentation for the final variant has been produced. Its design will lead to space saving in the laboratory and easier handling of test equipment in durability tests.
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Vibration of rolling bearing
Otoupalík, Jan ; Ripel, Tomáš (referee) ; Krejsa, Jiří (advisor)
The thesis deals with vibrations caused by geometric defect and fatigue damage of rolling element bearing. Hardware for vibration measurement is tested on 25 new pieces of NJ 304. Second part of the thesis examines if measuring of bearing vibration can help to detect a geometric defect. Geometric defects are detected according to a spectrum of vibration but the results are not absolutely exact. The possibility to detect geometric defects by measuring vibration has not been proven. The end of project tests diagnostic methods for rolling element bearings. The bearing defect was simulated to demonstrate bearing failure frequencies, envelope method and vibration spectrum.
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Bearings for machine spindles
Knápek, Jiří ; Nohál, Libor (referee) ; Galas, Radovan (advisor)
This bachelor’s thesis contains the survey of bearings for machine spindles. Thesis is especially focused on slide, air, magnetic and rolling bearings. Bearings are described with emphasis on their construction, lubrication and arrangements. In the end of this thesis there is a comparison of mentioned kinds of bearings for machine spindles.
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Effect of Conformity on Friction in Roller Bearing
Pisklák, Jan ; Zikmund, Vladimír (referee) ; Vrbka, Martin (advisor)
This master’s thesis describes the influence of conformity on friction in rolling bearings. The coefficient of friction is measured on an experimental machine - Mini Traction Machine 2 – using ball-on-disc method. The results are plotted in graphs which showing the dependence of the coefficient of friction at spin-to-roll ratio for specific conformity, normal load and speed in the contact area. The influence of load, speed or different lubricant viscosity is verified for a given value of conformity. Experimentally obtained data are compared with the mathematical model developed in MatLab, within this thesis.
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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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Surface treatment of roll bearings
Kubelka, Milan ; Klakurková, Lenka (referee) ; Švejcar, Jiří (advisor)
The bearings are one of the most widely used construction components enabling mutual movement of parts and at the same time transmission of interacting load. The basic requirements placed on components of roll bearings are particulary increase of contact fatigue resistance, decrease of the friction coefficient between the rolling bodies and bearing rings, increase of hardness and abrasion resistance of functional surfaces, the wear resistance, corrosion protection and finally the electrical and optical properties too. As production of bearings from materials with these attributes would be quite expensive, surface modifications are used for improving the mechanical properties. The main task of this bachelor thesis is description and evaluation of technologies suitable for surface treatment of roll bearings with increased attention to those types of surface treatment which, in cooperation with SVÚM will be studied in more detail in the experimental part of this work (especially polymer coatings, phosphate films and DLC - type coatings). The wear evaluation of different types of coatings was performed with the aid of scanning electron microscopy after the tribological testing.
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Turbocharger Rotors using Rolling Bearings
Šárovec, Marek ; Dlugoš, Jozef (referee) ; Novotný, Pavel (advisor)
The main purpose of this diploma thesis is to design turbocharger rotor using rolling element bearings. The diploma thesis is compiled from two specialized search parts dealing with turbocharger rotor and rolling element bearing computation, respectively. The application of the particular rotor using the multi body system Adams – View is described in the following chapter. In the last chapter, one can find the comparison between rotor using bearing with steal and hybrid ceramic rolling element. Also, there is compariosn between rolling element bearing and journal bearing. In the maximum rotor speed, the decrease of more than 50 % in power loss, due to usage of rolling element bearing, resulted from this comparison.
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