A method for controlling a vehicle installed with an automatic transmission, includes: a sudden stop determination step in which a controller determines whether the vehicle has stopped at a speed greater than or equal to a reference deceleration speed and whether a post-stop elapsed time is within a first reference time; a takeoff determination step in which the controller determines whether an input torque of the transmission exceeds zero within the first reference time when a shift range is in a driving range; a pressure control step in which, when the vehicle takes off, the controller elevates a line pressure of the transmission; a limitation determination step in which if a slippage extent of a turbine exceeds a reference slippage value for a second reference time, the controller limits the takeoff; and a torque reduction step in which the controller reduces a takeoff torque input of the transmission.

A method for operating a vehicle is disclosed. The vehicle has at least one torque transmission device which when rotating splashes in a fluid, at least two axles each having at least two wheels and at least one controllable coupling device adapted for selectively coupling or decoupling the torque transmission device with at least one of the wheels. The method includes the steps of: in an operating state in which no torque is requested by a driver of the vehicle, decoupling with the control device the torque transmission device and the at least one wheel when a driving speed of the vehicle is greater than or equal to a predetermined speed threshold value and coupling with the control device the torque transmission device and the at least one wheel for torque transmission when the driving speed is smaller than the predetermined speed threshold value.

A system and method for operating an automatic start/stop system in a motor vehicle having an internal combustion engine, an automatic transmission and a torque converter with an impeller disconnect clutch is disclosed. A controller may implement an engine start/stop system by, at appropriate times, stopping engine by halting fuel and restarting engine when propulsion is needed. During an engine start/stop event, the engine is automatically shut down and the impeller clutch of the torque converter may be disengaged to decouple the impeller and the engine to provide for fuel and emissions savings.

A drag torque reduction device for an automatic transmission includes a hydraulic controller with a diversion for excess cooling oil into an oil sump that is positioned upstream of a radiator relative to a flow of fluid to the radiator. The diversion includes a temperature-dependent, switchable aperture and a switching valve. The temperature-dependent, switchable aperture is configured to close above a temperature threshold. The switching valve is configured to close above a threshold pressure.

A drag torque reduction device for an automatic transmission includes a hydraulic controller with a diversion for excess cooling oil into an oil sump that is positioned upstream of a radiator relative to a flow of fluid to the radiator. The diversion includes a temperature-dependent, switchable aperture and a switching valve. The temperature-dependent, switchable aperture is configured to close above a temperature threshold. The switching valve is configured to close above a threshold pressure.

A drag torque reduction device for an automatic transmission includes a hydraulic controller with a parallel connection of a pressure relief valve, a constant aperture and a temperature-dependent, switchable aperture that is positioned upstream of a radiator relative to a flow of fluid to the radiator. The parallel connection is disposed between a first control edge of a converter switching valve and a first line. The first line leads to both to the radiator and through a check valve to the converter ring. The first control edge of the converter switching valve is open and lubricating oil flows through the parallel connection when the converter switching valve is in a first switching position. The first control edge of the converter switching valve is closed and lubricating oil does not flow through the parallel connection when the converter switching valve is in a second switching position.

A drag torque reduction device for an automatic transmission includes a hydraulic controller with a parallel connection of a pressure relief valve, a constant aperture and a temperature-dependent, switchable aperture that is positioned upstream of a radiator relative to a flow of fluid to the radiator. The parallel connection is disposed between a first control edge of a converter switching valve and a first line. The first line leads to both to the radiator and through a check valve to the converter ring. The first control edge of the converter switching valve is open and lubricating oil flows through the parallel connection when the converter switching valve is in a first switching position. The first control edge of the converter switching valve is closed and lubricating oil does not flow through the parallel connection when the converter switching valve is in a second switching position.

An electromagnetic control valve normality determination system includes: a hydraulic pressure source; an electromagnetic control valve structured to regulate an actual pressure of oil to a pressure command point, wherein the oil is supplied from the hydraulic pressure source; and an actual pressure sensor structured to sense the actual pressure of the oil. For determining normality of pressure regulation of the electromagnetic control valve, a normality determinator is configured to: set pressure command regions for determination about pressure regulation of the electromagnetic control valve, without overlapping among the pressure command regions; determine for each of the pressure command regions whether a difference between the actual pressure and the pressure command point in the each of the pressure command regions is less than a threshold value; and determine that the electromagnetic control valve is normal, in response to affirmation of the determination for all of the pressure command regions.

An electromagnetic control valve normality determination system includes: a hydraulic pressure source; an electromagnetic control valve structured to regulate an actual pressure of oil to a pressure command point, wherein the oil is supplied from the hydraulic pressure source; and an actual pressure sensor structured to sense the actual pressure of the oil. For determining normality of pressure regulation of the electromagnetic control valve, a normality determinator is configured to: set pressure command regions for determination about pressure regulation of the electromagnetic control valve, without overlapping among the pressure command regions; determine for each of the pressure command regions whether a difference between the actual pressure and the pressure command point in the each of the pressure command regions is less than a threshold value; and determine that the electromagnetic control valve is normal, in response to affirmation of the determination for all of the pressure command regions.

A control device for an automatic transmission includes a continuously variable transmission mechanism, a torque converter, a target transmission ratio calculation unit, a feedback control unit, and a phase compensation unit. The torque converter has a lock-up clutch. The target transmission ratio calculation unit is configured to calculate a target transmission ratio based on a travelling state. The feedback control unit is configured to perform feedback control based on an actual value indicative of a state of the continuously variable transmission mechanism. The phase compensation unit is configured to perform phase lead compensation of the feedback control based on the travelling state. The phase compensation control unit is configured to halt the phase lead compensation when an unstable travelling state of a vehicle is detected. The phase compensation control unit is further configured to release the lock-up clutch when the phase lead compensation is halted.