HYDRAULIC CONTROL SYSTEM OF AUTOMATIC TRANSMISSION FOR VEHICLE

摘要

PURPOSE: A hydraulic control system of an automatic transmission for a vehicle is provided to smoothly hold engine variable inertia by delaying the response property of hydraulic pressure released in N to D and D to N, and N to R and R to N shift and accordingly to prevent shift shock. CONSTITUTION: A hydraulic control system of an automatic transmission for a vehicle is composed of a lower part of a second pressure control valve(18) for supplying control pressure to a clutch operated at a D range and 1-speed; hydraulic-release control devices(60,62) disposed to the lower part of an N-R control valve(20) absorbing shock in shifting to an R range to control releasing hydraulic pressure; and a check valve(CB) for repressing the flow of hydraulic pressure toward the lower part. The check valve is arranged to a bypass pipeline(54) for connecting between the upper part of the second pressure control valve and the lower part of the hydraulic-release control device.