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Gear-shift process of automatic transmission (AT) can be achieved with hydraulic control system which operates clutches or brakes' engagement or disengagement. According to the state of engagement elements, gear-shift process can be divided into torque phase and inertia phase. This article analyses gear-shift process of automatic transmission with the lever analogy and got the variation of the transmission's output torque. Then, the control principle of clutch to clutch shift is studied. This article takes power on up shift as study example and minimum of transmission output torque fluctuations during shifting as control target. Then this article analysis two control principles including inertia phase engine & transmission integrated control principle and entire shift process engine & transmission integrated control principle.

In a traditional shift control strategy, the gear range is selected based on the throttle opening and the vehicle speed. The disadvantage of two-parameter based system is that the shift map is lack of adaptability in certain special conditions. The driving environment and the true intentions of the drivers are not fully taken into account by the shift control system. Therefore, improving the feasibility of the shift control strategy for the true intentions of the driver and driving environment is of great significance. Under braking conditions, Automatic transmission shift map with two parameters is unable to use engine braking effectively, which affects the drivability and safety of vehicles greatly. This paper presents a newly developed shift control strategy under braking conditions. First of all, the necessity of engine braking was analyzed.

According to the structural features and working characteristics of the dry clutch, this study focuses on the factors that affect the performance and life of the dry clutch. The temperature rise caused by the clutch slipping was proved as the key factor. Dynamics model of the powertrain for the dry clutch in launching process was established, and friction work generated during the launching process was simulated and calculated. Based on the basic theory of heat transfer, this paper defined the boundary conditions of the temperature field and the finite element model for the dry clutch was built. The transient temperature field of the friction disk, temperature field changes under the frequent starting conditions and the effects of friction material on temperature rise were analyzed, and measures were proposed to reduce the temperature of dry clutch from its design, use and control.

According to the low efficiency of vehicle equipped with automotive transmission (AT) at launching conditions, the TCCs slip and lock up control technology was proposed and a TCC simulation model was established. The vehicle dynamics, torque fluctuation and efficiency were analyzed. Simulation results were obtained when taking the constant engine speed as the control target. The three-dimensional transient heat conduction finite element model using CFX was built. The slipping power was calculated and was converted to heat flux on the surface of TCCs friction plate model. The temperature of TCCs friction plate was obtained at different ATF oil temperature. Simulation results show that the TCCs slip and lock-up control technology at launching conditions can effectively solve the vehicles low efficiency problems caused by torque converter (TC). The maximum temperature rise of TCCs friction plate was 20°C.

The battery electric vehicles (BEVs) equipped with automated manual transmission (AMT) can realize gear-shift automatically and show many advantages in terms of reduction of fuel consumption and improvement of driving comfort and shifting quality. This paper focuses on the gear-shift control strategy for a clutchless AMT in a battery electric bus. Compared with the traditional ICE vehicles, the studied battery electric bus has the different powertrain structure, which consequently requires a different gear-shift strategy. First, the so-called clutchless AMT means that the clutch usually used in the conventional AMT vehicles is removed. Second, the synchronizer within the transmission is omitted and that means only the sleeves are employed to accomplish engagement of gears. In order to find the key factors that affect gear-shift operation of AMT in battery electric bus, the several gear-shift phases including “Gear Release”, “Synchronization”, and “Gear Engagement” are modeled.

The battery electric vehicle (BEV) equipped with automatic mechanical transmission (AMT) can realize gear-shifting automatically based on the optimal shift schedule and thereby gains higher economy and dynamics performances as well as easy drivability. As one of electronic control systems in BEV, the AMT control system takes charge of drivetrain control and plays an important role. However, nowadays the development of electronic control systems in automobile industry is facing a variety of challenges which mainly arise from complex functional requirements and market pressure, and it's the same to the development of AMT control system. This paper presents a multi-layered and modular design approach for the development of AMT control system in a battery electric bus. The multi-layered design approach divides system into two high-level layers, each of which is then divided into a number of low-level layers.