Patent ID: 6319170
Filing Date: 2001-11-20
Classification: B60K,B60W,F16H,Y02T,Y10T

Abstract:
A method of controlling a power-on downshift of a vehicle automatic transmission from a current speed ratio to a target speed ratio, the transmission having an input shaft coupled to receive output torque from a vehicle engine, the method comprising the steps of:controllably releasing an off-going clutch of the transmission to allow the engine output torque to increase a speed of the input shaft toward a synchronization speed of the target speed ratio in accordance with a determined trajectory;periodically estimating a time to achievement of the synchronization speed by the input shaft;commanding a reduction in the engine output torque when the estimated time reaches a reference time corresponding lo an expected response delay in achieving a commanded torque reduction; andprogressively reducing the commanded reduction to zero when the input shaft achieves said synchronization speed.