Abstract: A transmission includes a latch valve with latched and de-latched states. In the de-latched state, the latch valve directs a control pressure to a clutch apply circuit. In the latched state, which is entered in response to a control pressure higher than a latch pressure, the latch valve directs a line pressure to the clutch apply circuit. A controller manages the transition from latched to de-latched differently depending upon the transmission input torque and gear state. At high transmission input torque, the controller first reduces the control pressure to rapidly accelerate a spool in the latch valve, and then increases the control pressure to prevent clutch slip. At low torque, the controller reduced the pressure to an intermediate value during the transition and then reduces it again. At moderate torques, the controller reduces the pressure directly to a target pressure in a single step.

Abstract: A transmission includes a latch valve with latched and de-latched states. In the de-latched state, the latch valve directs a control pressure to a clutch apply circuit. In the latched state, which is entered in response to a control pressure higher than a latch pressure, the latch valve directs a line pressure to the clutch apply circuit. A controller manages the transition from latched to de-latched differently depending upon the transmission input torque and gear state. At high transmission input torque, the controller first reduces the control pressure to rapidly accelerate a spool in the latch valve, and then increases the control pressure to prevent clutch slip. At low torque, the controller reduced the pressure to an intermediate value during the transition and then reduces it again. At moderate torques, the controller reduces the pressure directly to a target pressure in a single step.

Abstract: An automatic transmission ratio shift control system and method for a powertrain having a throttle-controlled engine and multiple-ratio gearing, torque flow paths through the gearing being established and disestablished by pressure-operated friction elements, an electronic controller for establishing torque transitions between the friction elements as ratio changes occur in the multiple-ratio gearing, the engine throttle being controlled by an electronic throttle control that is decoupled from the driver-controlled accelerator pedal, the transmission torque output being controlled by means of a friction element capacity control strategy including a feed-forward torque term determined by changes in commanded torque, the slip duration during a ratio change being controlled by means of closed-loop engine torque control.

Abstract: An automatic transmission ratio shift control system and method for a powertrain having a throttle-controlled engine and multiple-ratio gearing, torque flow paths through the gearing being established and disestablished by pressure-operated friction elements, an electronic controller for establishing torque transitions between the friction elements as ratio changes occur in the multiple-ratio gearing, the engine throttle being controlled by an electronic throttle control that is decoupled from the driver-controlled accelerator pedal, the transmission torque output being controlled by means of a friction element capacity control strategy including a feed-forward torque term determined by changes in commanded torque, the slip duration during a ratio change being controlled by means of closed-loop engine torque control.

Abstract: An automatic control strategy for use with a multiple-ratio transmission in an automotive vehicle driveline in which the crankshaft of an internal combustion engine is connected directly to torque input elements of multiple-ratio gearing without an intervening hydrokinetic torque converter. The strategy is adapted especially for use with a wet auto clutch to provide forward or reverse drive engagement during vehicle launch and during transient damping of driveline disturbances. The strategy makes it possible to control the clutches to achieve maximum vehicle acceleration by controlling the engine speed so that it operates at maximum torque throughout the useful engine speed range for any given engine throttle position. The entry and exit conditions for each drive mode are determined by the strategy so that optimum drive-away performance and optimum shift control, as well as soft clutch engagement and full clutch engagement, can be achieved.

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.