Dynamic simulation and valve structure optimization of an electro-hydraulic clutch shift control system in an automatic transmission

The electro-hydraulic clutch control system controls the transferred torque of gear-shifting clutches in clutch-to-clutch transmissions. A nonlinear dynamic model of an electro-hydraulic clutch shift control system is presented. The mechanical and fluid subsystems of all valves are investigated, including their interactions. Model validation of the electro-hydraulic valve system is performed by comparing the simulated and measured pressure curves. The dynamic characteristics of the electro-hydraulic clutch shift control system with different supply pressures and different fluid temperatures are simulated and evaluated. It is found that pipes which are often ignored between the electro-hydraulic valve system and the clutch piston, have strong influence on clutch piston chamber pressures. In order to satisfy the required time and reduce the fluctuation of the clutch piston chamber pressures, the orifices' diameters and valve structure are optimized.