Hydraulic control system of automatic transmission for vehicle provided with idle stop and go system

A hydraulic control system of an automatic transmission for a vehicle provided with an idle stop and go (ISG) system, the hydraulic control system configured to supply hydraulic pressure to at least one friction member of friction members operated at a gear stage where starting control is performed, the hydraulic control system comprising:

• a mechanical hydraulic pump driven by torque of an engine and configured to pump a fluid stored in an oil pan;
• a regulator valve configured to regulate hydraulic pressure fed from the mechanical hydraulic pump to be stable;
• a manual valve configured to receive the hydraulic pressure from the regulator valve through a first hydraulic line and to supply the hydraulic pressure to a second hydraulic line by manipulation of a shift lever;
• a linear solenoid valve configured to control the hydraulic pressure supplied from the manual valve through the second hydraulic line and to supply the controlled hydraulic pressure to a third hydraulic line;
• a first switch valve configured to selectively supply the hydraulic pressure supplied from the linear solenoid valve through the third hydraulic line to the at least one friction member through a fourth hydraulic line;
• and
• an electric hydraulic pump driven by electric energy and configured to pump the fluid stored in the oil pan through a fifth hydraulic line and to feed the pumped fluid to a second switch valve through a sixth hydraulic line,
• wherein the second switch valve is configured to supply the hydraulic pressure of the electric hydraulic pump supplied through the sixth hydraulic line to a seventh hydraulic line connected to the fourth hydraulic line, or to the second hydraulic line at an upstream side of the linear solenoid valve through an eighth hydraulic line.