Modeling And Simulation Of Heat Generation And Heat Transfer For A Dual Clutch Transmission

In the working process of transmission,the friction of moving parts such as bearings and gears will result in a certain power loss,which is released in the form of heat.If the lubrication system of transmission can not take away heat in time,the oil temperature will rise,the lubrication performance will decrease,resulting in excessive wear of moving pairs,and the transmission efficiency will decrease.Therefore,understanding the heat generation and temperature distribution of the transmission is a necessary link to reasonably design lubrication system and maintain high transmission efficiency.The work and main conclusions are as follows:?1?Through analysis and calculation,the calculation method of heat generation of each heat source is determined,and the influence of transmission operation and structure factors on heat generation of each heat source is analyzed.The results show that gear modulus,gear speed and bearing speed have the greatest influence on gear meshing loss,churning loss and bearing friction loss respectively.?2?According to the structure of the dual clutch transmission,the force acting on the gears and bearings are analyzed,and the bearing force calculation model is established based on AMESim software.Aiming at the limitation of AMESim software bearing module in the calculation of bearing heat generation,which is not suitable for transient conditions,the thermal simulation models of tapered roller bearings and deep groove ball bearings are established based on the determined calculation method of bearing heat generation and the development function of software.On this basis,the simulation model of transmission heat generation including heat generation calculation,bearing force calculation,heat distribution and gear control is established.The model can be used to simulate the heat generation under steady and transient conditions.?3?According to the structure and lubrication mode of dual clutch transmission,the heat transfer path between the nodes is analyzed,and the transmission are discretized.Based on the thermal network theory,the corresponding thermal network structure is established and the heat transfer model of the transmission is built based on AMESim software.According to the heat conduction and convection forms of each part,corresponding calculation methods of thermal resistance are determined and completed.?4?Coupled the heat generation and heat transfer model,and applied the coupled model to simulate and verify the heat generation and heat transfer of the transmission under the 6^th gear steady state conditions of input speed and torque are 2160 r/min and182.4 Nm,respectively.The results show that the simulation results are in good agreement with the experimental results,and the maximum relative error of temperature at each measuring point is less than 3.7%.Among all heat sources,gear meshing loss accounts for 50.3%,followed by clutch sliding loss and churning loss accounts for the smallest;the equilibrium temperature of oil is 112.0?,slightly higher than the normal working temperature;the average temperature of gear teeth of 6^th gear drive gear and367R intermediate shaft is higher,which are 164.9?and 128.8?,respectively,within the normal working permission of the material.Considering oil temperature and the surface flash temperature of gear contact pair are higher than the average temperature of gear teeth,if the transmission works more frequently under this condition,the heat dissipation of oil cooler should be increased and the oil cooling system should be strengthened.?5?On the basis of the test conditions,the heat generation and heat transfer of the transmission are simulated only by changing the ambient temperature.The results show that with the increase of ambient temperature,the oil viscosity decreases gradually,the friction loss of bearings and the churning loss of gears decrease gradually,the meshing loss of gears increases gradually,and total heat generation and heat dissipation of housing are basically constant values.When ambient temperature increases from 0?to40?,the corresponding oil temperature increases from 91.0?to 131.3?,and oil temperature has gradually exceeded the normal temperature range.At this time,it is necessary to gradually increase the heat dissipation of oil cooler,and maintain the oil temperature within the normal working range.?6?The heat generation and heat transfer under transient conditions are simulated by using the model.The results show that the heat generation of clutch under complete slip states is much larger than that of gear and bearing at all times;the total loss fluctuates obviously due to the change of speed and torque during shift;and the oil temperature fluctuates three times due to the complete slipping of clutch,the maximum oil temperature is 103.2?;the highest temperature is steel disc of odd gear clutch,the maximum temperature is 215.3?.The difference between the temperature of other working parts and the temperature of oil is not too large,which is in a reasonable range.