METHOD OF CONTROLLING SPEED RATIO IN AUTOMATIC SPEED CHANGE GEAR

摘要

PURPOSE: To provide a controlling method for shifting from an off-going torque transmission of hydraulic operation type associated with the first speed ratio to an on-coming torque transmission of hydraulic operation type associated with the second speed ratio in an automatic transmission for an automobile. CONSTITUTION: Upshifting is controlled by ramping down the pressure in an off-going clutch C1-C5 associated with a high speed and increasing the pressure in an on-coming clutch C1-C5 associated with a lower speed ratio. The on-coming clutch C1-C5 has commanded pressure at a maximum value for an initial fill time, a lower increasing ramp value during the ramp of the off-going clutch until the on-coming clutch starts to engage, and then closed-loop control until the clutch reaches a synchronous speed. Parameters for controlling the quality of a shift are automatically adjusted during vehicle use to correct shift aberrations which degrade shift quality.