Patent ID: 7344466

Claim:
A hydraulic control system of a seven-speed automatic transmission for a vehicle, comprising: a first clutch control portion controlling a forward range pressure according to a control of a first proportional control solenoid valve so as to supply the forward range pressure to a first clutch at first, second, third, fourth, and fifth forward speeds and preventing hydraulic pressure from being supplied to the first clutch when the first proportional control solenoid valve is turned off at fourth, fifth, sixth, and seventh forward speeds; a first brake and third clutch control portion controlling and selectively supplying the forward range pressure to a first brake or a third clutch according to a control of a second proportional control solenoid valve at the fourth, fifth, sixth, and seventh forward speeds, a low L range, and a reverse R range and maintaining a hydraulic line to the third clutch at the fourth, fifth, sixth, and seventh forward speeds in the case that an on/off solenoid valve controlling a spool valve controlling the hydraulic line to the third clutch malfunctions to be turned off; a second clutch control portion supplying a line pressure to a second clutch according to a control of a third proportional control solenoid valve at the third, fifth, and sixth forward speeds and a reverse speed; a second brake control portion supplying the forward range pressure to a second brake according to a control of a fourth proportional control solenoid valve at the second and seventh forward speeds and controlling an operating pressure of the second brake to be larger at the seventh forward speed than at the second forward speed; and a fourth clutch control portion supplying an operating pressure to a fourth clutch according to a control of a fifth proportional control solenoid valve at the first, second, third, fourth, sixth, and seventh forward speeds and the reverse speed.