Device and method for controlling line pressure of hydraulic control system for 4-speed automatic transmission

摘要

A device and a method of a hydraulic control system for 4- speeds automatic transmissions which may reduce line pressure in a steady flow during operation of an automotive vehicle at high speed thereby decreasing the load applied to an oil pump and reducing fuel consumption. And when shifting from the second, third or fourth speed of the "D" range, where the damper clutch operates, to another shift range, which makes it so the line pressure is not changed when the damper clutch is released thereby increasing the load applied to the engine, thereby preventing the run-up of the engine, and when the shift is completed, which changes the line pressure again, thereby improving shift quality and power transmission efficiency.