Line pressure control system for automatic transmission

摘要

An automatic transmission has a transmission gear mechanism for transmitting the engine output power by way of a plurality of power transmission paths, and friction engagement elements which are operated by a line pressure from a control valve to change the power transmission path through the transmission gear mechanism. Feed of the line pressure is controlled by a throttle pressure corresponding to the engine load and a governor pressure corresponding to the output speed of the transmission gear mechanism to effect gear shifting. A line pressure control system for controlling the line pressure comprises a regulator valve for regulating the line pressure, and a throttle modulator valve for determining a throttle modulator pressure for controlling the regulator valve according to the governor pressure and the throttle pressure so that the line pressure is increased with increase of the throttle pressure and is lowered with increase of the output speed of the transmission gear mechanism.