Patent ID: 6193630
Filing Date: 2001-02-27
Classification: B60W,F16H,Y10T

Abstract:
A method of controlling a powershift transmission of an engine-driven vehicle, the transmission having a fluid pressure operated clutch for controlling flow of torque through the transmission, said clutch being off-going during a shift of the transmission, and a pressure control valve for controlling fluid pressure communicated to the clutch in response to a valve control current applied to an input thereof, the clutch having an input element and an output element, the method comprising:applying a slip pressure to said clutch so that relative rotation (slip) between the input and output elements of said clutch occurs;determining an amount of torque transmitted through said clutch as a function of a slip pressure recorded at a time said clutch begins to slip;determining, after the clutch has begun slipping and as a function of said determined amount of torque, a pressure increase, which when applied to said slipping clutch would allow said slipping clutch to continue to slip while transmitting substantially the same torque it was transmitting before it began to slip; andapplying said determined pressure increase to said slipping clutch.