MULTI-STAGE-TRANSMISSION-HYDRAULIC-CIRCUIT EQUIPPED PREVENT-OIL-LINE POSSIBLE DRIVNG ON LIMP-HOME-MODE

摘要

The present invention relates to a hydraulic circuit comprising: a hydraulic line to respectively supply hydraulic pressure to at least one friction element equipped in a transmission; multiple solenoid valves equipped in the hydraulic line to control the hydraulic pressure supplied to one among friction elements; multiple switch valves equipped in the hydraulic line to control flow of the hydraulic pressure; and a parking release maintaining valve to receive the hydraulic pressure through the hydraulic line. Moreover, the hydraulic circuit comprises: an operating valve equipped to be adjacent to at least one solenoid valve to connect the solenoid valve with the friction element, and to block the solenoid valve from the friction element and to connect the switch valve with the friction element when the hydraulic pressure is supplied through the switch valve; and a preventing flow path formed in the hydraulic line to press the other switches in order to prevent malfunction when one among the switch valves is operated. The hydraulic line is divided into a first branch flow path connected with the solenoid valve, a second branch flow path selectively connected with the solenoid valve or the operating valve according to operation of the switch valve, and a third branch flow path having an ON/OFF solenoid valve to operate the switch valve, so the preventing flow path is formed in the hydraulic line. Therefore, provided is the hydraulic circuit for a multi-stage transmission capable of running a limp home mode having the preventing flow path having an effect of preventing a control means in an SBW type from malfunctioning in a normal operating state or a limp home mode state by preventing malfunction of an R switch valve, a D switch valve, and a P switch valve operated by the ON/OFF solenoid valve.