Method and apparatus for speed change control of an automotive automatic transmission

摘要

During downshift operation of an automotive automatic transmission in which a lower-speed clutch for establishing a lower-speed gear is engaged while a higher-speed clutch, which has established a higher-speed gear, is disengaged, to increase the turbine rotational speed Nt toward a synchronous rotation speed Ntj associated with the lower-speed gear, speed change control is carried out according to the same control method regardless of whether the engine is in a power-on or power-off state. A target change rate (Nir)' of turbine rotational speed associated with the higher-speed clutch and a target change rate (Nia)' of turbine rotational speed associated with the lower-speed clutch are set, and a change rate (Nt)' of the turbine rotational speed is detected. The transmission torque through the higher-speed clutch is controlled in a feedback manner such that the detected change rate (Nt)' coincides with the change rate (Nir)'. Further, the transmission torque through the lower-speed clutch is feedback-controlled such that the change rate (Nt)' coincides with the change rate (Nia)', thereby carrying out downshift.