Patent ID: 7314423
Filing Date: 2008-01-01
Classification: F16H,Y10T

Abstract:
1. A hydraulic control system of a six-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, and fourth forward speeds and preventing hydraulic pressure from being supplied to the first clutch when the first proportional control solenoid valve is turned-off at fifth, and sixth 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, and sixth forward speeds, a low L range, and a reverse R range and maintaining a hydraulic line to the third clutch at the fourth, fifth, and sixth 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 and fifth forward speeds and a reverse speed; and 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 sixth forward speeds and controlling an operating pressure of the second brake to be larger at the sixth forward speed than at the second forward speed.