Research On The Control Strategy Of Light Commercial Vehicle AMT Starting And Shift Decision

Electronically controlled Automated Manual Transmission(AMT)is widely used in the field of commercial vehicles due to its excellent performance in fuel consumption rate,manufacturing cost,production inheritance,transmission efficiency,etc.However,there is a synchronous shock when the clutch is engaged in the starting phase,which causes the vehicle to produce an instantaneous frustration,which seriously affects the comfort of the driver and passengers.On the other hand,the AMT vehicle has an unreasonable shifting schedule,which causes the vehicle to have a cycle shift problem,Affecting the safety of the vehicle.In view of the above problems,this thesis combines the enterprise engineering project with light commercial vehicle AMT as the research object,carries out the AMT vehicle starting control and shifting law research,improves the starting and gear decision control strategy,and effectively solves the synchronous impact and impact of the vehicle starting process.The problem of gear shifting cycles during driving has been verified by actual vehicle tests.The main content and basic conclusions of the paper are as follows:Aiming at the synchronous shock problem during the start of AMT vehicles,this thesis studies the zero synchronous shock starting control strategy based on engine torque compensation.First,analyze the characteristics of the clutch and establish the clutch dynamics and engine model.Secondly,the power requirements,ride comfort requirements and low slip friction requirements of light commercial vehicles were clarified,and control parameters were selected and set according to the requirements.Finally,by compensating the engine torque at the time of synchronization,the impact of the vehicle’s starting synchronization is eliminated.Aiming at the unreasonable shifting rules of the vehicle during the driving process,which causes the problem of cyclic shifting of the vehicle,this thesis studies the gear decision control strategy based on vehicle mass estimation.First,the normalized load of the vehicle is analyzed,and then the method based on the kinetic energy theorem is used to estimate the vehicle mass.Finally,on the basis of the vehicle mass estimation,based on the conventional shifting rule,the vehicle speed during the shift is compensated,The gear selection method based on traction and driving resistance is adopted.Finally,this thesis uses a certain type of light commercial vehicle as a test platform to carry out actual vehicle road tests.The test results show that the starting control strategy based on engine torque compensation effectively eliminates the synchronization shock during the start of AMT light commercial vehicles.The gear decision control strategy based on vehicle mass estimation effectively avoids the shift cycle phenomenon when the vehicle is driving on a slope,and basically satisfies the driving demand of the vehicle.