Abstract: A hydraulic control system of an automatic transmission may be applied to an automatic transmission in which a reverse speed stage is engaged by engagement of first and second friction elements. The hydraulic control system may include: a first solenoid valve being a normally open type and controlling a line pressure to generate a first hydraulic pressure; a second solenoid valve being a normally closed type and controlling the line pressure to generate a second hydraulic pressure; first and second switch valves, the first switch valve selectively supplying the first hydraulic pressure to the second switch valve; and a fail-safe valve selectively supplying the first hydraulic pressure or the second hydraulic pressure to the second friction element, wherein the second switch valve selectively supplies the first hydraulic pressure supplied from the first switch valve or a reverse speed pressure to the first friction element.

Abstract: A circuit for controlling hydraulic pressure of a torque converter that includes an engagement hydraulic pressure chamber independently installed in a fluid operation chamber enclosed by a front cover and an impeller and having engagement hydraulic pressure supplied to engage a lock-up clutch may include a torque converter control valve stably decreasing line pressure and supplying the decreased line pressure as operation hydraulic pressure of the torque converter, a torque converter pressure control valve controlled by a linear solenoid valve to control D range pressure and supply the controlled D range pressure to the engagement hydraulic pressure chamber, and a lock-up switch valve controlled by the linear solenoid valve to supply the hydraulic pressure supplied from the torque converter control valve as control pressure of the torque converter pressure control valve and supply exhaust hydraulic pressure of the torque converter as control pressure of the torque converter control valve.

Abstract: A hydraulic control system of an automatic transmission may be applied to an automatic transmission in which a reverse speed stage is engaged by engagement of first and second friction elements. The hydraulic control system may include: a first solenoid valve being a normally open type and controlling a line pressure to generate a first hydraulic pressure; a second solenoid valve being a normally closed type and controlling the line pressure to generate a second hydraulic pressure; first and second switch valves, the first switch valve selectively supplying the first hydraulic pressure to the second switch valve; and a fail-safe valve selectively supplying the first hydraulic pressure or the second hydraulic pressure to the second friction element, wherein the second switch valve selectively supplies the first hydraulic pressure supplied from the first switch valve or a reverse speed pressure to the first friction element.

Abstract: A hydraulic pressure supply system of an automatic transmission may include a low-pressure oil pump generating low hydraulic pressure while being driven by an engine to exhaust the low hydraulic pressure to a first low-pressure channel, a high-pressure oil pump raising a portion of the hydraulic pressure in the first low-pressure channel to a high pressure while being driven by an electric motor to exhaust the hydraulic pressure to a first high-pressure channel, a low-pressure regulator valve controlling the hydraulic pressure while exhausting a portion of the hydraulic pressure to supply the controlled hydraulic pressure to a low-pressure part through a second low-pressure channel, and a high-pressure regulator valve controlling the hydraulic pressure while re-circulating a portion of the hydraulic pressure to the low-pressure part through single or two re-circulation channels according to the pressure to supply the controlled hydraulic pressure to a high-pressure part through the second high-pressure channe

Abstract: A circuit for controlling hydraulic pressure of a torque converter that includes an engagement hydraulic pressure chamber independently installed in a fluid operation chamber enclosed by a front cover and an impeller and having engagement hydraulic pressure supplied to engage a lock-up clutch may include a torque converter control valve stably decreasing line pressure and supplying the decreased line pressure as operation hydraulic pressure of the torque converter, a torque converter pressure control valve controlled by a linear solenoid valve to control D range pressure and supply the controlled D range pressure to the engagement hydraulic pressure chamber, and a lock-up switch valve controlled by the linear solenoid valve to supply the hydraulic pressure supplied from the torque converter control valve as control pressure of the torque converter pressure control valve and supply exhaust hydraulic pressure of the torque converter as control pressure of the torque converter control valve.

Abstract: A hydraulic pressure supply system of an automatic transmission may include a low-pressure oil pump generating low hydraulic pressure while being driven by an engine to exhaust the low hydraulic pressure to a first low-pressure channel, a high-pressure oil pump raising a portion of the hydraulic pressure in the first low-pressure channel to a high pressure while being driven by an electric motor to exhaust the hydraulic pressure to a first high-pressure channel, a low-pressure regulator valve controlling the hydraulic pressure while exhausting a portion of the hydraulic pressure to supply the controlled hydraulic pressure to a low-pressure part through a second low-pressure channel, and a high-pressure regulator valve controlling the hydraulic pressure while re-circulating a portion of the hydraulic pressure to the low-pressure part through single or two re-circulation channels according to the pressure to supply the controlled hydraulic pressure to a high-pressure part through the second high-pressure channe

Abstract: A hydraulic control apparatus may be provided with a lock-up clutch operated or not by hydraulic pressure difference between an engagement-side oil chamber and a disengagement-side oil chamber and may include a first hydraulic line supplying hydraulic pressure to the disengagement-side oil chamber or exhausting the hydraulic pressure from the disengagement-side oil chamber, a second hydraulic line supplying hydraulic pressure to the engagement-side oil chamber or exhausting the hydraulic pressure from the engagement-side oil chamber, and a third hydraulic line connected to a slip switch valve, and selectively exhausting through the slip switch valve the hydraulic pressure supplied to the engagement-side oil chamber.

Abstract: A hydraulic pressure control system for a torque converter includes a lock-up clutch operated according to pressure difference between an engagement and disengagement side oil chambers, a first hydraulic line communicated with the disengagement side oil chamber, second and third hydraulic lines communicated with the engagement side oil chamber, and a lock-up switch valve and a torque converter hydraulic pressure control valve that generate pressure difference between the second and the third hydraulic line communicated so that fluid within the engagement side oil chamber is circulated in lock-up on state of the lock-up clutch, and the lock-up switch valve and the torque converter hydraulic pressure control valve generate pressure difference between the second and the third hydraulic line in slip state of the lock-up clutch higher than the pressure difference between the second and the third hydraulic line in the lock-up on state of the lock-up clutch.

Abstract: An auto transmission hydraulic control apparatus may include six friction elements that of which two friction elements operate to achieve a corresponding to each stage by hydraulic pressure, five direct-controlled solenoid valves that individually and directly control hydraulic pressure to four friction elements and equally and directly control hydraulic pressure to the other two friction elements, an on-off solenoid valve converting output state and non-output state of hydraulic pressure, a switch valve in which one side of a valve spool is supplied by a spring to selectively supply hydraulic pressure from one of the direct-controlled solenoid valves, equally and directly controlling the hydraulic pressure supplied to the two friction element, in accordance with whether hydraulic pressure from on-off solenoid valve is applied to the other side thereof, and four fail-safe valves disposed between the direct-controlled solenoid valves and the friction elements to structurally limit available arrangements of the

Abstract: A hydraulic pressure control system for a torque converter includes a lock-up clutch operated according to pressure difference between an engagement and disengagement side oil chambers, a first hydraulic line communicated with the disengagement side oil chamber, second and third hydraulic lines communicated with the engagement side oil chamber, and a lock-up switch valve and a torque converter hydraulic pressure control valve that generate pressure difference between the second and the third hydraulic line communicated so that fluid within the engagement side oil chamber is circulated in lock-up on state of the lock-up clutch, and the lock-up switch valve and the torque converter hydraulic pressure control valve generate pressure difference between the second and the third hydraulic line in slip state of the lock-up clutch higher than the pressure difference between the second and the third hydraulic line in the lock-up on state of the lock-up clutch.

Abstract: An auto transmission hydraulic control apparatus may include six friction elements that of which two friction elements operate to achieve a corresponding to each stage by hydraulic pressure, five direct-controlled solenoid valves that individually and directly control hydraulic pressure to four friction elements and equally and directly control hydraulic pressure to the other two friction elements, an on-off solenoid valve converting output state and non-output state of hydraulic pressure, a switch valve in which one side of a valve spool is supplied by a spring to selectively supply hydraulic pressure from one of the direct-controlled solenoid valves, equally and directly controlling the hydraulic pressure supplied to the two friction element, in accordance with whether hydraulic pressure from on-off solenoid valve is applied to the other side thereof, and four fail-safe valves disposed between the direct-controlled solenoid valves and the friction elements to structurally limit available arrangements of the