Shift quality of transmission system for construction vehicle

The mechanical models were developed for engine,working pump,torque converter and automatic transmission in the transmission system of construction vehicle,and the dynamical equation was deduced.To describe the shift characteristics,the torque and motion of the clutches of automatic transmission were discussed during shifting.The relations were derived analytically among the angular velocity,torque of gearbox,rotational velocity,throttle opening of engine and torque converter quotient.The impact of the parameters of engine and torque converter on shift quality was derived.To improve the shift quality,the cushion valve control,timing control and their combination control for engine-transmission system were developed.Finally,a simulation test for transmission system was carried out to validate the availability of control algorithm and to test the integrated performance of shift quality.The results show a significant improvement in terms of shift quality by applying valve control,timing control and their combination control.