Research On Shift Quality Of High Horsepower Tractor Fixed-Axis AT Variable Speed Drive System

Transmission is an important part of the vehicle.Heavy commercial vehicles,large buses and agricultural tractors and other high-power vehicles,usually use combined transmission based on power shift system.Power shift transmission are easy to operate,shift fast,can improve the overall performance of the vehicle.The main content of this subject is analysing the shift quality,based on high-power tractor with fixed-axle 4AT +6MT combined transmission,The details are as follows:(1)The overall introduction of the target model is proposed,and overall transmission scheme of the fixed-axle combined transmission is proposed according to the target model;(2)Based on the internal structure of front,middle and rear box of load-shifting transmission,the transmission route of 4D + 4R power shift module is analyzed;(3)The force analysis of the target vehicle model is carried out.the vehicle dynamics model of high horsepower tractor is established.State of two pairs of clutch of the tractor is divided into three states in clutch shift process,respectively,the model is established in every states and mutual transfer condition of three states in two pairs of clutches is put forward;(4)According to the vehicle dynamics model,modeling and simulation analysis of the typical operation is completed based on Matlab / Simulink;(5)The shift quality and evaluation index is put forward during tractor shift,the influencing factors of the shift quality is analyzed,the way of coordinating feedback control of the engine is put forward to reduce the speed loss during shift.Finally,the relationship between shift time and shift Jerk is proposed.A shift control strategy is put forward with the target of reducing shift Jerk of tractor when the shift time is satisfied;(6)Experiment bench is designed,the experiment contents and procedures is given.