| As the core component of automotive transmission,the synchronizer eliminates the rotational speed difference between the two ends of the synchronizer by the friction torque generates during the friction synchronization to achieve synchronous shift.The performance of the synchronizer directly determines transmission's performance.During the friction synchronization,a large amount of frictional heat generates,which causes the temperature between the friction pairs to rise,eventually resulting in a decrease of the friction coefficient,thus affecting shift performance.In this paper,the coefficient of friction of the lock-ring synchronizer is taken as the research object,and a synchronizer test-control platform was built to obtain the friction coefficient MAP.Based on the friction coefficient MAP,the friction coefficient compensation control strategy of the synchronizer was established.The effectiveness of the compensation control strategy was verified by simulation and experiment.The major works of the subject includes the following aspects:(1)The synchronization process of the lock-ring synchronizer was studied.The synchronization time,shock degree,sliding-friction work are used as parameters for evaluating synchronization performance.The mathematical model of the shifting actuator and synchronization process was established,then the simulation model of synchronization process was completed in Matlab/Simulink.The influence of friction coefficient's change on synchronization performance was analyzed by simulation.(2)A synchronizer test-control platform was built,the hardware system and software system of the platform was completed.Based on the test-control platform,the friction test was carried out under different working conditions,and the initial friction coefficient MAP was obtained by collecting signals during the test.The initial MAP was optimized through bicubic interpolation method,and then the interpolated friction coefficient MAP was generated.(3)Based on the friction coefficient MAP,a friction coefficient compensation control strategy was proposed.Using the minimum principle,the optimal control for the shift synchronization process was completed,and the optimal shifting force trajectory was obtained to limite the shifting force obtained by friction coefficient compensation control.A simulation model of friction coefficient compensation control for synchronization process was built,and the synchronization process was analyzed by simulation.Simulation results show that:when the synchronous initial rotational speed difference is 600r/min and the rotational inertia of synchronized partial is 0.04kg?m~2,the synchronization time before compensation is 0.70s,synchronization time after compensation is 0.62s,and the latter is shortened by 0.08s compared to the former.The final value sliding-friction work of the synchronization phase before compensation is 77.89J,the final value sliding-friction work after compensation is 73.25J,the latter is shortened by 4.64J compared to the former.The effectiveness of the friction coefficient compensation control strategy was verified by comparing the simulation results before and after compensation.(4)Based on the friction coefficient compensation control strategy,the compensation control module was added to the synchronizer test-control platform.The test plan of friction coefficient compensation control was formulated,and the test was completed.The results show that:when the synchronous initial rotational speed difference is 600r/min and the rotational inertia of synchronized partial is 0.04kg?m~2,the synchronization time before compensation is 0.87s,synchronization time after compensation is 0.74s,and the latter is shortened by 0.13s compared to the former.It is verified that the designed friction coefficient compensation control strategy can significantly shorten the synchronization time,thus reduce the shift interruption time,which is of great significance for improving the shift quality. |
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