Transmission control system for multi-ratio gear arrangement

Abstract

The disclosed control system regulates changes of gear ratio in an automatic transmission for a vehicle. A supervisory control arrangement monitors operator input commands through the shift range selector lever, and receives a desired-ratio command either from a shift point computer or from a manual gear shift selector. When the supervisory control arrangement determines that the desired-ratio signal differs from the actual ratio, the monitoring function is interrupted and a shift-initiate command is provided. This command is utilized to assign certain components for use in a shift quality control arrangement, for effecting the controlled ratio change. A torque output signal from the vehicle drive line is used in conjunction with the shift quality control arrangement. After the shift is completed, the previously assigned components are released and the supervisory control arrangement resumes the monitoring of the desired ratio as contrasted to the actual gear ratio. One circuit controls all the upshifts, whether 1-2, 2-3, or 3-4, and one other circuit controls all the downshifts. This assignment of certain components for each controlled ratio change, and their release so they can be re-used in subsequent ratio changes, contributes to a cost-effective trade-off between the number of circuits required in the total system and the complexity of the logic circuits actually employed.