Caterpillar Inc.

James R Talbott

Randall M Mitchell

Todd D Creger

Alan L Stahl

Richard B League

Gregory L Williamson

David M Spurlock

The present invention is directed toward determining when a clutch of an automatic transmission substantially fills with fluid. Once it is accurately determined when a clutch fills with fluid, then control over the transmission shifting may reliably be performed. The present invention determines when an on-coming speed clutch substantially fills with fluid in response to determining when an off-going speed clutch releases. Further, the present invention determines when an on-coming direction clutch substantially fills with fluid in response to determining when the torque converter output torque suddenly changes.

Method for determining the fill time of a transmission clutch

The present invention relates to an adaptive control method for an automatic transmission. The method includes the steps of:

Adaptive control method for an automatic transmission

In one aspect of the present invention, a method for controlling an interrupted shift for a powershift transmission is disclosed. The method first determines which clutches are active and then classifies each of the active clutches. Thereafter, the method calculates the timing associated with the engagement and disengagement of the classified active clutches to result in a smooth transition to the final selected gear.

Method of controlling interrupted shifts for a powershift transmission

In one aspect of the present invention, an electronic shift control for a powershift transmission is disclosed. The transmission includes a plurality of speed and direction changing clutches. A plurality of pressure control valves are individually connected to the clutches. A hydraulic pump delivers pressurized hydraulic oil to predetermined pressure control valves to meter hydraulic fluid in response to receiving a clutch command signal. The method produces a shift from a first transmission ratio to a second transmission ratio through disengagement of an off-going clutch associated with the first transmission ratio and engagement of an on-coming clutch associated the second transmission ratio. The method includes filing an on-coming speed clutch, releasing an off-going direction clutch in response to the on-coming speed clutch being filled, and thereafter, gradually increasing the on-coming speed clutch pressure to engage the speed clutch. Finally, the on-coming direction clutch pressure is gradually increased to engage the direction clutch in response to the on-coming speed clutch being engaged.

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Fitchburg, MA, United States of America

James R Talbott