| Summary: | 碩士 === 中原大學 === 機械工程研究所 === 94 === In this study, the method of predicting temperature distribution has been established in the design of cooling system for the bearing chamber to decrease the bearing temperature. The bearing chamber is assumed to two-dimension symmetrical model which is assumed symmetrical about vertical axis and is divided into different parts based on heat conduction of structure, frictional heat of bearing, boundary condition, forced air cooling, cooling pipe and heat exchange. The representative nodes were set in each part and the temperature distribution of bearing chamber are obtained by using thermal network method to perform analysis of heat equilibrium.
The temperature of bearing chamber is varied with the friction-induced heat which is influenced by the friction momentum and viscosity of lubrication oil. Therefore, this thesis utilizes the Newton-Raphson method to determine the temperature of bearing chamber. The value of viscosity depended on temperature varying can be yielded by substituting initial temperatures into the transform formula of the lubrication oil. Then, the friction momentum can also be yielded to compute heat generation according to the value of viscosity obtained. Finally, the heat generation is substituted into the equations of thermal equilibrium iteratively to progress convergent analysis until iterative errors are small enough and satisfied the precision demand.
The thermal deformations of a bearing are induced due to the heat generation from friction and magnet in motor. Also, lower performance of bearing is yielded since the distribution of temperature is not uniform. Consequently, the cooling systems including fan and pipe are adopted in this thesis to decrease temperature rising in the bearing chamber. Furthermore, the life of a motor can be extended due to discarding considerable heat by increasing flow quantity from cooling systems.
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