The present invention relates to the foreign matter flowing in the circuit in the hydraulic circuit of the automatic transmission that can be quickly removed effectively.
Hydraulic pressure in the automatic transmission according to the embodiment of the present invention circuit, a hydraulic circuit of an automatic transmission for supplying the hydraulic pressure to a plurality of friction elements provided in the automatic transmission to implement a plurality of shift speed, the operation required for the friction element hydraulic so that the solenoid proportional control valve for controlling the hydraulic supply; The supply passage is provided with the proportional control solenoid valves and connecting the friction element, and the control in the proportional control solenoid valves so that the hydraulic pressure supplied to the friction element; And a switch valve which is interposed on the supply passage to selectively open and close the supply passage; It may include.