Research On AMT Clutch Control During Start Process

Automated mechanical transmission(AMT)competes the clutch separation and engagement,gear shift and the coordination of the engine,by the microcomputer control system equipped on the traditional mechanical transmission instead of driver.Compared with other types of automatic transmission,AMT conforms more to the current transmission development of China,because of low costs in production and maintenance.During start process of the car,clutch engagement control directly affects the driving comfort and the service life of the clutch,which is the key and difficult point of AMT development.In this paper,a certain passenger car quipped with AMT is taken as research object to mainly study the engagement of clutch during process of start,design control strategy in order to start rapidly and improve the driving comfort.The main contents of this research are as follows:(1)analyzed the load and torque characteristics of diaphragm spring clutch and the operation performance,control methods of AMT actuator(2)analyzed the vehicle dynamic characteristics during start process and the causes of impact and friction works;according to the changing rules of vehicle status during clutch engagement;chose engine speed,clutch driven disc speed,throttle opening,clutch displacement as control parameters to design the engagement strategy of “P-Fuzzy-PI” and “Constant-Fuzzy-Constant”,taking the max connect speed of clutch as limit condition.(3)built AMESim-Simlink co-simulation model consisting of vehicle dynamics and control unit to verify the feasibility of the proposed control strategy on condition of three classic throttle opening(20%,50%,80%)and then adjusted the relevant parameters to improve the control strategy according to the simulation results.(4)with modular design ideas,completed the controller C language programs in CodeWarrior environment,including applications and underlying programs(Speed acquisition module,Analog signal acquisition mosule Serial communication module,Timer module,Motor drive module,etc)(5)built test bench of based on the transmission test bench to study clutch engagement during start process and the tset results of smooth start were basically in accordance with the simulations results for “fast-slow-fast” connect rules.