A clutching device of an automatic transmission may include a clutch drum connected to a first rotation element, a clutch connected to the clutch drum and a second rotation element, and a piston device to operate the clutch, wherein the piston device may include a first piston forming a first sealed space with the first rotation element and the clutch drum and moving toward the clutch by a hydraulic pressure supplied to the first sealed space, a second piston forming a second sealed space with the first piston and moving toward the clutch to directly press the clutch by a hydraulic pressure supplied to the second sealed space, a spring retainer disposed on the first rotation element and forming a third space with the second piston and the first rotation element, and a return spring stored in the third space and abutted by the spring retainer and the second piston.

The present disclosure provides a hydraulic control system for an automatic transmission. The system includes: a linear solenoid valve configured to control a line pressure and to supply the line pressure to a coupling element, a shift valve to which an output hydraulic pressure of the linear solenoid valve is supplied, and a transmission control unit configured to control the shift vale and the linear solenoid valve.

A control device of a vehicle power transmission device including a first power transmission path transmitting power by engaging a first clutch, a sub-clutch and a second power transmission path transmitting power by engaging a second clutch each disposed between an engine and drive wheels and parallel to each other, the device including a fail-safe valve for preventing simultaneous engagement of the first and second clutches, the fail-safe valve configured to be switched to a fail-safe spool position preventing simultaneous engagement of the first and second clutches by a hydraulic pressure of a hydraulic fluid supplied to the first clutch or an output pressure of a first electromagnetic valve controlling the hydraulic pressure and the hydraulic pressure of the hydraulic fluid supplied to the second clutch or an output pressure of a second electromagnetic valve controlling the hydraulic pressure, the second electromagnetic valve configured to increase the output pressure.

A clutch latching system is provided for latching and draining a torque transmitting mechanism. The latching clutch control system may include a latching valve, a release valve, and an accumulator. The clutch latching system may include a clutch feed channel configured to provide hydraulic fluid from a pressurized source to a torque transmitting device when the torque transmitting device is engaged and the engine is running. A latching valve connects the clutch feed channel to the torque transmitting device. The latching valve is configured to selectively trap pressurized hydraulic fluid within the torque transmitting device. A hydraulic pressure storage circuit configured to selectively provide pressurized hydraulic fluid to the latching valve to unlatch the latching valve. A multiple speed transmission is also provided.

A hydraulic control system includes a hydraulic pump driven by an electric motor, a solenoid valve having an output that controls the positions of a pressure regulator valve and a third, stator shift valve. The solenoid valve is a normally high, variable force solenoid valve which provides a control signal to the second and third valves. The second, pressure regulator valve is a multiple port valve which controls hydraulic fluid flow both to a transmission oil cooler (ATOC) and to an exhaust port, thereby maintaining a desired system pressure. The third, stator shift valve is also a multiple port valve and it controls fluid flow to the stator of the electric pump motor to provide cooling and to a dog clutch of the transmission to disengage it.

A method for controlling clutch pressure in an electronically controlled limited slip differential comprises receiving a target clutch pressure command indicative of a desired differential torque transfer setting. Processing the target clutch pressure command comprises estimating one of a motor current or a motor speed, calculating an integrated error of a target motor current or an integrated error of a target motor speed, calculating gains over time based on the estimated motor current or the estimated motor speed and based on the integrated error of the target motor current or the integrated error of the target motor speed, applying the calculated gains thereby forming a closed loop feedback, and calculating an oscillation. The target motor current or the target motor speed is applied to a motor connected to a clutch in the differential according to the calculated oscillation to control the clutch pressure of the differential.

A driving-force transmitting apparatus 1 includes first and second friction clutches, a piston that presses the first and second friction clutches, a hydraulic pump that feeds hydraulic oil to a cylinder chamber in the piston, an electric motor that drives the hydraulic pump, and a control apparatus that controls the electric motor to adjust the discharge pressure of the hydraulic pump. The control apparatus has a feedback control apparatus that controls the electric motor using a correction value based on a deviation between a target value and an actual value of the discharge pressure of the hydraulic pump, a hydraulic-oil temperature estimating apparatus that estimates a temperature of hydraulic oil, and a gain adjusting apparatus that changes a correction amount for feedback control in accordance with the estimated temperature of the hydraulic oil.

A hydraulic control system for vehicle includes: an engine; an oil pump driven by the engine; a clutch device brought into engagement to enable power transmission between the engine and drive wheels by delivering a pressurized fluid thereto, and brought into disengagement to interrupt the power transmission between the engine and the drive wheels by discharging the fluid therefrom; and an accumulator storing the fluid delivered to the clutch device. The hydraulic control system is configured to control the hydraulic pressure applied to the clutch device, to stop the engine while bringing the clutch device into disengagement upon satisfaction of a predetermined stopping condition, and to restart the engine while bringing the clutch device into engagement upon satisfaction of a predetermined restarting condition. In the hydraulic control system, a hydraulic circuit increases flow rate of the fluid flowing between the accumulator and the clutch device when the engine is stopped.

In one instance, disclosed herein is a pressure modulating clutch control assembly that includes: a valve assembly configured to apply a clutch pressure to a clutch device; a pressure modulation assembly in fluid communication with the valve assembly and configured to control a maximum pressure level that the clutch pressure reaches; and a modular relief valve in fluid communication with the valve assembly and the pressure modulation assembly, the modular relief valve forming part of a hydraulic feedback loop between the valve assembly and the pressure modulation assembly, wherein the hydraulic feedback loop is configured such that an increase in a modulation pressure of a pressurized fluid within the pressure modulation assembly causes a corresponding increase in the clutch pressure until the clutch pressure reaches the maximum pressure level.

In one instance, disclosed herein is a pressure modulating clutch control assembly that includes: a valve assembly configured to apply a clutch pressure to a clutch device; a pressure modulation assembly in fluid communication with the valve assembly and configured to control a maximum pressure level that the clutch pressure reaches; and a modular relief valve in fluid communication with the valve assembly and the pressure modulation assembly, the modular relief valve forming part of a hydraulic feedback loop between the valve assembly and the pressure modulation assembly, wherein the hydraulic feedback loop is configured such that an increase in a modulation pressure of a pressurized fluid within the pressure modulation assembly causes a corresponding increase in the clutch pressure until the clutch pressure reaches the maximum pressure level.