Patent ID: 6577939
Filing Date: 2003-06-10
Classification: F16H,Y10T

Abstract:
A pressure control system for a multiple-ratio, geared, power transmission mechanism for an automotive vehicle powertrain including an engine and a torque output shaft drivably connected to vehicle traction wheels, the transmission mechanism having pressure-operated friction elements for selectively activating multiple torque flow paths through the transmission mechanism and actuators for selectively actuating and deactivating the friction elements;an electronic controller for developing a desired gear ratio in the transmission mechanism in response to driveline operating variables and driver commanded operating variables, the controller including memory registers for storing transmission control algorithms and a processor unit for executing the control algorithms to establish a desired destination gear ratio in a ratio change sequence in response to the operating variables; the electronic controller including a first subsystem for processing changes in the desired destination gear by identifying active friction elements, by selecting the gear ratio change sequence, by selecting pressure profiles for each friction element involved in a ratio change, and by timing of the start and completion of each ratio change; a second subsystem for specifying the pressure control action required to apply or release a friction element during a ratio change and during a friction element engagement, the second subsystem comprising a library of pressure profiles required to complete all ratio changes and engagements; and a third subsystem for storing a collection of pressure calculations and algorithms accessible by the first and second subsystems for calculating an appropriate pressure for each friction element.