Abstract: A control strategy and method for controlling application and release of friction elements in an automatic transmission to effect gear ratio changes as one friction element is release and another friction element is applied during ratio changes. The transmission has an electronic controller and multiple solenoid regulator valves hydraulically coupled directly to pressure-operated friction elements. Powertrain variables are obtained and processed to calculate gear ratio control parameters derived from desired line pressure for a pressure control valve circuit that communicates with the friction elements. The desired gear ratio is determined for each given set of powertrain variables. Upshifts and downshifts are obtained by releasing one friction element in synchronism with an application of the other friction element, whereby a direct friction element to friction element torque transition is achieved with minimal inertia torque disturbances.

Abstract: An adaptive electronic transmission control for an automatic transmission having multiple-ratio gearing establishing plural torque flow paths between a torque input member and a driven member, the relative motion of the elements of the gearing being controlled by a friction torque establishing member and an overrunning coupling connection between two gear elements of the gearing. A ratio shift is achieved by establishing a driving connection between a selected gearing element and a torque delivery shaft. The shift is achieved by controlling the capacity of the friction element using a fluid pressure actuator. Shift quality is optimized by establishing a bias pressure on a friction element accumulator and by using a feedback control system to control the rate of change of transmission ratio during the shift.

Abstract: An adaptive control system and method for direct clutch engagement control for an automatic transmission including a micro-controller that receives and stores input data from driveline sensors and executes transmission clutch control logic. The micro-controller develops output signals in real time and transfers the signals to a driver circuit that controls solenoids that enable clutch engagement. The signals for establishing clutch pressure buildup are delivered to a driver circuit that produces hydraulic pressure at the clutch to achieve a smooth torque and speed transition for the torque input elements of the transmission. Adaptive pressure values are stored in a keep-alive memory. The pressure values are adjusted values based on the result of previous engagements. This compensates for driveline variables such as changes in coefficients of friction, spring loads, clutch wear, etc.