| Speed control system as the vital part of the transmission system,has long been regarded as the focus of technological innovation.The friction synchronization time of synchronizer is very short during the synchronous shift phase,but the friction coefficient of the friction cone will change due to the presence of frictional heat,thus the control accuracy of synchronizer’s shift will be affected.In this paper,the inertial type of synchronizer is taken as the research object.Theoretical analysis,simulation and experimental study are employed,the fem software-ANSYS Workbench is used to analyze the temperature changing regularities of synchronizer’s friction cone during the synchronization process.Developed a friction and wear test bench for synchronizer,the temperature changing regularities of synchronizer’s friction cone during the synchronous process was studied by experiment.The friction coefficient changing regularities of the friction cone is analyzed preliminarily,which lays the foundation for establishing the compensation strategy of synchronizer’s friction coefficient during the synchronous shift phase.The specific work of this research includes the following aspects:(1)Analyze the theory of friction to heat during the synchronization process.The theoretical basis of heat transfer is studied,three basic forms of heat transfer are analyzed and it is determined that ways of synchronizer’s heat transfer during synchronization process are heat conduction and thermal convection.The generalized differential equation of heat conduction is established,and the complementary conditions for solving differential equation about synchronization process are determined.The method of solving the thermal-structural coupling analysis about synchronization process is determined.(2)Finite element model about synchronizer’s thermal-structural coupling analysis during synchronization process is established.A 3D model about synchronizer is established through the3-d software-CATIA,and the model is simplified under the premise of ensuring the computational accuracy.According to the actual synchronizer’s material type,determine model’s material parameters,choose analytical unit’s form,and complete the model’s hexahedral meshing.According to the theoretical basis of thermal-structural coupling and practical working conditions,thermal boundary conditions and mechanical load boundary conditions are determined.(3)Analyze and calculate synchronizer’s thermal-structural coupling during synchronous process.Through the finite element model of synchronizer,the thermal-structural coupling analysis of synchronous process under different workingconditions is completed,the temperature changing regularities of synchronous process is studied preliminarily,at the same time,the influence of load and speed on the maximum temperature of the synchronizer is analyzed qualitatively.(4)Experimental study on synchronizer’s synchronous process.Aimed at synchronizer’s shift process,we develop a friction and wear test bench.Based on the test bench,we study the temperature changing regularities of synchronous process under different working conditions.The results of the experiment show that during synchronous process,the maximum temperature of synchronous ring’s friction surface increases by about 1.85 ℃ for every additional 50 N of shifting force and the maximum temperature of synchronous ring’s friction surface increases by about 2.1°C for every additional 200r/min speed difference.By comparing the results of the experiment and those of the simulation,we find that deviation is around 11% and verify the accuracy of simulation results.Friction coefficient changing rules of synchronizer’s friction cone during synchronous process is preliminarily analyzed,which lays the foundation for establishing the compensation strategy of synchronizer’s friction coefficient,it is of great significance to improve the accuracy of synchronizer’s shift control. |
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