| When the tractor is carrying out the traction operation,because of the high resistance,if the power is interrupted during the shifting process,the tractor's working speed will be sharply reduced,or even the engine will stop.The use of power shift transmission can ensure continuous power in the process of shifting,thus improve the productivity and work quality of the tractor.In order to improve the performance of tractor transmission in China and realize agricultural modernization as soon as possible,the shift law and the optimal control of shift quality of power shift transmission are studied in this project,the main research work is as follows:(1)The structure,shifting method,power transmission route of each gear,the characteristics of key components in the transmission system and the tractor's working resistance characteristics are analyzed,and the tractor transmission system model is built based on MATLAB / Simulink.(2)The basic shifting law of tractor's two parameter dynamic performance is formulated.At the same time,considering the influence of the tractor drive wheel slip rate,on the basis of analyzing the relationship between the slip rate and the driving force and traction efficiency,a kind of shift correction strategy is proposed which takes the throttle opening and the slip rate as the control parameters.This strategy can control the slip rate of the driving wheel in the best range on the premise of ensuring the power performance of the tractor,which is suitable for various types of operation under the condition of traction resistance,so that the tractor has high traction efficiency.(3)By analyzing the relationship between the speed of the clutch drive and driven discs during the power shift process,proposed a clutch control strategy that can avoid power cycling.Then,the dynamic analysis of the shifting process is carried out,and the simulation model of the shifting process is established to verify the effectiveness of the proposed clutch control strategy.(4)In order to improve the shift quality,this paper takes oil pressure and oil pressure change time of key nodes of the control strategy as optimized parameters,and take sliding friction work,jerk and output torque oscillation amplitude as optimization objectives,optimize shift quality by the improved particle swarm genetic algorithm,and carry out the sliding mode control of clutch pressure,which can effectively improve shift quality.(5)By analysis of the relationship between the engine speed and the speed of clutch drive-driven disk,and based on the optimized clutch control oil pressure of improved particle swarm genetic algorithm,an engine speed control strategy which can make the clutch drive-driven disk speed quickly synchronize by adjusting the engine speed is proposed,which can reduce the sliding friction work generated during the shift process and shorten the shift time.In order to achieve a good control effect,a fuzzy adaptive PID controller of clutch speed difference to be combined is designed. |
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