HYDRAULIC CIRCUIT FOR EIGHT SPEED TRANSMISSION IMPLEMENTED ISG FUNCTION AND SBW FUNCTION

摘要

The present invention relates to a hydraulic circuit installed in a powertrain for transmitting power, including: a plurality of solenoid valves installed in hydraulic lines for controlling a plurality of friction elements of transmissions; a plurality of fail-safe valves installed in the hydraulic lines for selectively controlling the hydraulic pressure which is supplied to function as the friction elements when the solenoid valves are in de-energized; a plurality of position valves installed in the hydraulic lines and selectively supplied with the hydraulic pressure from ON/OFF solenoid valve which is operated by an electric signal ordering the transmission to operate one among the transmission ratio of reverse, neutral, and forward to be moved to communicate with at least one among the solenoid valves; and a hydraulic pressure storage equipped for selectively supplying the hydraulic pressure to the hydraulic lines by storing the hydraulic pressure which flows in the hydraulic lines when pumps of hydraulic lines stop. The hydraulic circuit for an eight-speed transmission having the ISG function and SBW function realizes the improvement of shift quality, reduction of the assembly man hour and components, simplification of the structure using direct solenoid valves, SBW function to improve driver convenience, ISG function having the hydraulic storage to pressurize the hydraulic lines during the pumps are not functioning, and the ISC and SBW functions which have various fail-safe valves to realize the limp home mode.