Hydraulic control system of automatic transmissions

Claim 1

A hydraulic control system, for an automatic transmission of the type including an engine-driven torque converter having at least one stator vane, speed change gears connecting the torque converter to an output shaft, and hydraulic servos controlling components of the speed change gears, said hydraulic control system comprising, in combination, respective hydraulic pressure sensing openings in the suction and pressure sides of at least one stator vane of said torque converter for supplying the respective hydraulic pressures on said suction and pressure sides; a pressure regulator valve connected between a source of hydraulic fluid, under a pressure variable with engine speed, and said servos, and regulating a line pressure applied to said servos; and means controlling said pressure regulator valve in accordance with said respective hydraulic pressures on said suction and pressure sides of said stator vane to regulate the line pressure applied to said servos in accordance with variations in said respective hydraulic pressures on said suction and pressure sides of said stator vane. A hydraulic control system for an automatic transmission, as claimed in claim 1, in which said means comprises a control valve modulating the control pressure effective on said pressure regulating valve and including a movable valve element having said respective hydraulic pressures on said suction and pressure sides applied to respective opposite ends thereof.