| A transmission is one of the main parts of vehicle transmission systems, whose working condition has a significant influence on vehicles’ performances. Since a transmission has compact structure and serious operating condition, if the lubrication system lacks of the enough ability of heat transfer so that the heat cannot be taken away immediately when the transmission is operating, the temperature of the lube oil and transmission parts will become much higher, which result in abnormal operation of the transmission. Therefore, in order to ensure that a transmission can operate normally in various working conditions, the temperature of the lube oil must be keep in a suitable range. Therefore, this dissertation focuses on the simulation and analysis of the flow and heat transfer of the light-duty automobile. The main research contents and conclusions are as follows:①. The calculation method for internal heat production of the transmission is introduced. The influences of structure parameters, working condition, lube oil parameters and et.al on heat production from each heat production source were analyzed, and the corresponding influence law has been summarized.②. The simulation model of transmission’s internal heat production and the bearing force-distributed model were set up based on AMESim software. The simulation coupling the two models will be able to be realized under different working conditions.③. The heat transfer path of the transmission was analyzed, and the heat transfer path diagram was drawn. Then model coupling the internal heat production and heat transfer models was set up with AMESim software based on the heat transfer path diagram. The heat balance analysis can be achieved with the coupling model under different working conditions.④. Calculation methods of the convection heat transfer coefficient between the main components of transmission and lube oil, as well as between gear box outer wall and air were selected according to the various convection heat transfer conditions.⑤. Internal heat production was obtained under various working conditions. The results show that the total heat production from 5th and 6th gears is larger than other gears, and the mesh loss of operating gear pairs in the transmission are the main heat sources. Besides, the bearing heat production is mainly affected by the input speed and load and paddling losses is relatively small.⑥. The temperature profile of lube oil and the main components of the transmission, and the balancing temperatures under various working conditions have been obtained. The results show that when the heat transfer between exterior wall of the transmission and the surrounding is nature convective, the balance temperature of lube oil and the main components of the transmission lie in the required temperature range for 1st to 4th gears, but the temperature for 5th and 6th gears is higher than the required value so that the transmission can not operate normally and permanently.The balance temperature of the lube oil has been reduced to the required temperature range by using a water-cooled radiator. |
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