Research On Shift Schedule And Evaluation Method Of Automotive Automated Manual Transmission

Due to its advantages of simple structure, high transmission efficiency, low cost, good manufacturing succession, etc., Automated Manual Transmission (AMT) holds an important place in the automatic transmission family, and has been listed as key projects starting from the national "Eighth Five-Year Plan" to the national "Eleventh Five-Year Plan" in China. Therefore, research and development of AMT not only fits the situation of our country, but also can realize automatization-alteration and increase market-competition capability for vehicles made in our country.AMT realizes the automatic control of vehicle starting, gear-position selecting and gear-shifting via adding computer control system on the traditional mechanical transmission. In the vehicle equipped with AMT, shift schedule is a crucial issue in automatic transmission control system that affects the performance matching between engine and transmission, i.e., the dynamic performance and fuel economy of vehicle, directly.Shift Schedule determines the time when an automatic transmission vehicle should shift from one gear position to an adjacent gear position. The control parameter of shift schedule can be divided into single-parameter (velocity), 2-parameters (velocity and throttle) and 3-parameters (velocity, throttle and acceleration). According to the optimization objective, shift schedule can be classified into optimal dynamic and economical shift schedule. The research of this paper is focused on the computation and evaluation methods of optimal dynamic and fuel-economical shift schedules with 3-parameters.Vehicle usually runs under the non-stable conditions of acceleration or deceleration, therefore, to get satisfactory 3-parameters shift schedule, a match between engine and transmission must be taken into account and a precise description for engine dynamic torque and fuel consumption characteristics is required. In this paper, engine stable test data of Santana 2000 sedan were revised and fitted to build dynamic torque and fuel consumption models.Based on the traditional optimal 3-parameter dynamic and fuel-economical shift schedule making methods, the improved optimal dynamic and fuel-economical shift schedule making methods were proposed and used to calculate corresponding shift schedules for Santana 2000 sedan in accordance with drive-train related parameters and built engine models, respectively.For the purpose of shift schedule evaluation, simulation models of engine and drive-train, as well as a simulation-based shift schedule evaluation model were established using Matlab/Simulink. The gear-shifting processes were simulated on the basis of the drive-train related parameters of Santana 2000 sedan, and the improved and unimproved dynamic and fuel-economical shift schedules were used respectively in the processes of simulation-based evaluation. The conclusions are summarized as follows: gear-shifting repetition on slope and changes of jerk are greatly decreased by the improved optimal dynamic 3-parameter shift schedule;and the computation complexities as well as fuel consumption are reduced by the improved optimal fuel-economical 3-parameter shift schedule.