立式馬達軸承室之熱網路分析 及軸承溫昇估算

Thermal Network Analysis for Bearing Chamber of Vertical Motor and Estimation of Temperature Rising for Bearings

黃亭章(Ting-Zhang Huang)

指導教授 ： 張永鵬 ； 康淵

中原大學/工學院/機械工程學系/碩士(2006年)

https://doi.org/10.6840/CYCU.2006.00496

摘要

本文主要的目的是建立軸承箱溫度分佈預測方法及設計冷卻系統方案，藉以降低軸承溫度。預測時，假設軸承箱為二維軸對稱模型，且根據結構熱傳導，軸承摩擦生熱，溫度邊界，強制通風冷卻及冷卻水管熱交換等區分成不同區域，並在各區域中設立代表性節點，以熱網路法進行節點熱平衡分析，計算出軸承箱的溫度分佈。
由於本系統的摩擦熱量受摩擦力矩所影響，摩擦力矩又與潤滑油黏度有關，且潤滑油黏度又隨溫度變化而不同，因此，本文採用Newton-Raphson Method將初始溫度值代入潤滑油之溫度與黏度換算公式，得到潤滑油黏度值，再經由潤滑油黏度值推算得到摩擦力矩，並利用摩擦力矩計算得到摩擦生熱量後，代入節點熱平衡方程式進行溫度收斂性分析，直至誤差達許可值為止。
軸承受馬達電磁生熱及摩擦熱所影響，易造成軸承溫度分佈不均而產生熱變形，影響其工作性能，因此，本文採用冷卻風扇及冷卻水管散熱系統來對軸承箱進行冷卻，藉由增加冷卻風扇及冷卻水的流量，使其帶走更多的熱量來降低軸承箱的溫昇，以延長馬達之壽命。

關鍵字

摩擦熱 ； 溫昇 ； 熱網路 ； 軸承

並列摘要

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.

並列關鍵字

Frictional heat ； Bearing ； Thermal network ； Temperature rise.

參考文獻

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4. T.A. Harris, Rolling Bearing Analysis,4th ed., John Wiley &Sons, 2001.

5. T.A. Harris, “Prediction of Temperature in a Rolling Bearing Assembly, Lubrication Engineering,” pp. 145-155, 1964.

6. R. A. Burton, “Thermal Aspect of Bearing Seizure,” Wear, pp. 157-173, 1965.