Automatic transmission digital control system

摘要

Constants for reconstructing by straight line approximations a plurality of characteristic shift curves each plotting limiting engine load vs. engine speed are stored in a main storage. A speed counter furnishes a binary speed number indicating present engine speed and a load counter furnishes a load number indicative of the actual position of the gas pedal. Output logic furnishes address control signals selecting the constants stored in the main storage for a particular characteristic curve in response to the load and speed numbers and a present gear signal. From these a limiting load number is computed. A comparator compares the present load number to the limiting load number and output logic furnishes a selected gear shift control signal if the comparator output is indicative of the correct relationship between the limiting and actual loads for the desired shift. The main pressure in the automatic transmission is also controlled and desired gear shift signals from a driver operated gear selector are blocked if the engine speed exceeds corresponding permissible upper speed limits.