| The current domestic tractors usually adopt manual shift transmission.Manual shift transmission often requires large operating force to shift,In order to meet the requirements of field operations,tractor transmission usually set more gears and the driver needs to operate the clutch constantly in order to change the gear,which can easily cause the driver fatigue.This thesis chose manual shift transmission of one tractor as the research object.Partial gears were achieved electronic pneumatic shift by the improved design of the structure of the transmission and research results at home and abroad for reference and China's national conditions.The static and dynamic performance of the improved transmission system were analyzed and optimized by means of theoretical calculation and simulation.Research was mainly focused on components' static performance,the dynamic characteristics of transmission housing and the dynamic response of gear system.The main research work was described as follows:(1)The whole design scheme of electronic pneumatic shift system was determined according to structure characteristics of the transmission.Shift actuator and the structure of housing were redesigned,and the principle of electronic controlled pneumatic system was completed.(2)One rigid-flexible coupling model of transmission was established based on ROMAX,which was used to analyze static characteristics of gears,shafts and housing,including intensity checking calculation of shafts,bearings,housing and gears,predication of bears' useful life,analysis for distribution of bearings' internal load and stress,and the misalignment of gears.(3)The free mode and constraint mode of transmission housing were analyzed with ROMAX,analyzed the characteristics of mode shapes.And analyzed whether the resonance phenomenon will appear or not when the transmission was working by comparing gear mesh frequencies with the natural frequencies of housing.(4)Analyzed the causes of the dynamic excitation in gear system,and analyzed the gear transmission error based on the rigid-flexible coupling model of transmission,studied the dynamic response of the gear system on the basis of considering the coupling effect of gears' meshing stiffness and transmission error.The static and dynamic performance of the transmission system were optimized by modification of tooth profile,and some effect were achieved with optimization.Partial gears were achieved electronic pneumatic shift,which can reduce the driver fatigue,improve productivity,and enhance the market competitiveness of enterprise products.What' more,the static and dynamic performance of the transmission system were analyzed and optimized,which can provides reference for enterprise's further research on transmission. |
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