Ford Motor Company Limited

Ernest S Sametz

Eileen A Schock

Timothy J Kropf

A technique for controlling the rate of engagement of a friction element in response to a commanded change in operating range of an automatic transmission. Hydraulic pressure at a blip magnitude fills the hydraulic cylinder of a friction element. The pressure magnitude at the base of a pressure ramp and a magnitude at the top of the ramp are calibrated over a range of transmission oil temperature for each type of range change required by the vehicle operator. The calibrations minimize the length of engagement and produce a smooth engagement. Execution of an algorithm produces a high level of pressure magnitude on the basis of these calibrated values, a step down at the base of a ramp, a rate of increase during the period of engagement, and a maximum pressure at the top of the ramp.

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Allen Park, MI, United States of America

Ernest S Sametz