Abstract: A torque converter control valve in a fluid system of a four-speed automatic transmission for controlling the line pressure from the pressure regulator to the torque converter of the automatic transmission.

Abstract: Reciprocating valves in a fluid system of a four-speed automatic transmission having grooves that collect and shed dirt and other contaminants which may inhibit the operation of the valves.

Abstract: A double-acting spring in a four-speed automatic transmission to locate and return a clutch apply piston in a non-applied position between a plurality of clutch assemblies.

Abstract: A fluid actuated switch valve in a four-speed transmission to direct fluid flow between solenoid-actuated valves and a clutch apply piston in a low gear position and in a high gear position, while allowing one of the solenoid-actuated valves to also direct fluid flow to the lock-up piston of a torque converter in the high gear position.

Abstract: A method of determining and controlling a lock-up of a torque converter in a four-speed automatic transmission for full or partial frictional coupling between the torque converter and the vehicle engine. The method includes the steps of checking conditions that preclude partial lock-up operation and unlocking the torque converter if partial frictional coupling is precluded. The method also includes setting initial conditions for going from unlock to partial frictional coupling and checking for conditions that allow full frictional coupling operation. The method further includes fully frictional coupling the torque converter if conditions allow full frictional coupling operation, otherwise, partially frictionally coupling the torque converter.

Abstract: A method of reducing stall torque from the engine to the transmission based on a desired engine speed to minimize the potential interference and possible damage to any of the electronically controlled transmission components for an automatic transmission.

Abstract: A method of monitoring an output and adjusting the action affecting the output continuously for an electronic automatic transmission system wherein a controller is programmed to "learn" from the results of its operation. The method includes monitoring the speed of an input member and the instantaneous fluid volume of a friction element. The method also includes setting a learned volume value equal to an instantaneous fluid volume whenever the input speed is within a predetermined range of a predetermined speed. The method further includes comparing the learned volume value to a stored fill volume value at the end of the shift and adjusting the stored fill volume value based on the difference between the learned volume value and the stored fill volume value.

Abstract: A method of torque phase shift control for an electronic automatic transmission system to determine the apply rate of a fluid actuating device and adjusts the same to match the torque build-up of the apply element to the torque fall-off of the release element during shifting of the transmission.

Abstract: A method of reducing the shift torque from the engine to the automatic transmission system in response to predetermined conditions existing in the transmission so as to minimize the potential interference and possible damage to any of the electronically controlled transmission components.

Abstract: A method of adaptively idling a transmission in an electronic automatic transmission system putting the transmission to "neutral" when the engine is idling and the brakes are applied.

Abstract: Pressure balanced pistons in a four-speed automatic transmission which prevent the centrifugal force acting on the rotating fluid in the clutch cavity from causing the piston to remain in the clutch applied position even though the fluid apply line is vented.

Abstract: A method of sensing and determining open circuits and short circuits to the solenoid-actuated valves for the electronic automatic transmission.

Abstract: A method for controlling the apply element during a kickdown shift for an electronic automatic transmission system by controlling the turbine speed along a desired slope to adaptively predict how much time remains to fill the apply element after having achieved a predetermined target speed for the turbine.

Abstract: A method wherein a controller is programmed to determine the acceleration of the turbine in the torque converter to control transmission operation during a shift or gear change by counting the number of teeth during a predetermined cycle and dividing that tooth count by the actual time elapsed between the first and last tooth in an automatic transmission.

Abstract: A method of reverse clutch operation prevents excessive wear of the reverse clutch in a four-speed automatic transmission by venting one clutch, filling the reverse clutch and applying it, and filling and reapplying the one clutch.

Abstract: A method of adaptively scheduling a shift or inhibiting a shift until engine speed is at least equal to or greater than the output speed of the target gear which will prevent any negative torque, and will eliminate any "clunk" in the drivetrain in an automatic transmission system.

Abstract: A fluid actuated switch valve is provided in a four-speed transmission to direct fluid flow between solenoid-actuated valves and a clutch apply piston in a low gear position and in a high gear position, while allowing one of the solenoid-actuated valves to also direct fluid flow to the lock-up piston of a torque converter in the high gear position.

Abstract: A method of shift selection in an electronic automatic transmission wherein a controller is capable of selecting between various desired transmission gear changes or shift patterns to place the transmission in the appropriate gear based on a plurality of input conditions. The method includes comparing a mask with a byte in a table row and determining whether a matching row was found. The method also includes pointing to the next row if a matching row was found and determining whether the present operating gear equals the next byte. The method further includes selecting the next byte to perform a predetermined gear change or selecting another byte to perform another predetermined gear change based on the present operating gear equaling the next byte, and executing the gear change selected.

Abstract: A push-pull clutch apply piston of a four-speed automatic transmission which utilizes a clutch apply piston with a single pressure plate being pushed by fluid pressure in one direction for applying a clutch assembly and being pulled in an opposite direction for applying an adjacent clutch assembly. The piston has an axially extending flange at an outer periphery thereof, and at least one pressure plate retained to the flange.

Abstract: A method of controlling the speed change of a kickdown shift for an electronic automatic transmission system by predicting how much time remains to fill the apply element after having achieved a predetermined target speed for the turbine of the torque converter.