An abnormality determination device for a continuously variable transmission is provided in which since the abnormality determination device which calculates a compression stiffness of a metal belt from an amplitude ratio between a variable component of the rotational speed of an input shaft and a variable component of the rotational speed of an output shaft, a phase lag that is an indicator of the difference in phase between a variable component of the rotational speed of the input shaft and a variable component of the rotational speed of the output shaft, and a belt pitch radius of a drive pulley or a driven pulley, and determines whether a metal ring has broken by comparing the compression stiffness of the metal belt with a preset reference compression stiffness.

A method of controlling engine torque according to transmission hydraulic pressure is performed by an engine torque control system of a vehicle. The method includes connecting an engine torque converter to an engine and an automatic transmission of the vehicle, calculating a required turbine torque after confirming an engine torque control condition, deriving and storing a value of turbine torque factor learning through turbine torque factor learning according to shift type and shift time, converting the stored value of turbine torque factor learning into an engine torque control value, and requesting the engine torque control value to be applied to engine output, by an engine torque controller during shifting of the automatic transmission, so that a new turbine torque calculation is performed through a hydraulic pressure reference at the beginning of physical shifting, thereby preventing a shift shock and transmission damage caused by unreasonably excessive or insufficient engine torque.

A method of adjusting deceleration dependent shift points to maintain a target minimum turbine speed includes calculating a vehicle speed offset based on vehicle acceleration rate a predicted downshift delay for the target minimum turbine speed and converting the target minimum turbine speed to a target vehicle speed based on the deceleration condition. Thereafter, the method continues with determining a target gear based on the vehicle speed offset and the target vehicle speed, and downshifting to the target gear having vehicle speed less than or equal to a vehicle speed corresponding to the current turbine speed. The method ends with maintaining the target gear until a shift delay period is greater than a predetermined delay threshold.

The present invention is a control device for an automatic transmission, the control device being adapted to control the automatic transmission including a torque converter and a stepped transmission mechanism provided on a power transmission route from the torque converter to drive wheels, wherein while a non-driving range of the automatic transmission is selected, determination on interlock in the stepped transmission mechanism is executed on the basis of deceleration of an output shaft of the stepped transmission mechanism and a change in the torque converter.

A method (200) for open-loop control of a gearbox (100) that includes a first and a second proportionally controllable shift element (A-F) is provided. The method (200) includes disengaging the first shift element (A-F) of the gearbox (100) according to a first control profile and engaging the second shift element (A-F) of the gearbox (100) according to a second control profile. The first control profile comprises a variable portion (330) which is increased between a first point in time (t4), when a gradient (335) of the rotational speed of an input shaft of the gearbox (100) reaches a predetermined threshold value, and a second point in time (t5), when the gradient (335) flattens.

A method for controlling a gear ratio of a continuously variable transmission vehicle includes: a step of detecting a position of a shift lever by a controller; a step of checking, by the controller, a gear ratio variation based on a difference between a desired stage gear ratio and a current gear ratio in a continuously variable transmission when the shift lever is detected to be positioned in a manual range; a step of calculating, by the controller, a gear ratio correction value based on a rate of change of engine RPM when the gear ratio variation is checked as being other than zero after the step of checking the gear ratio variation; and a step of correcting, by the controller, the gear ratio variation in response to the calculated gear ratio correction value after the calculation step.

When a power transmission path of a power transmission system is set to a second power transmission path, a continuously variable transmission is controlled at a speed ratio () that provides a higher vehicle speed in the case where an input shaft angular acceleration (di/dt) is small than in the case where the input shaft angular acceleration (di/dt) is large. Therefore, it is possible to control the speed ratio () of the continuously variable transmission to a speed ratio () that reflects an inertial loss (Tli) of the continuously variable transmission. The inertial loss (Tli) changes with the input shaft angular acceleration (di/dt). Thus, in a vehicle in which the continuously variable transmission and a gear mechanism are provided in parallel with each other between an input shaft and an output shaft, it is possible to appropriately reduce a loss of the idling continuously variable transmission.

A method of adjusting deceleration dependent shift points to maintain a target minimum turbine speed includes calculating a vehicle speed offset based on vehicle acceleration rate a predicted downshift delay for the target minimum turbine speed and converting the target minimum turbine speed to a target vehicle speed based on the deceleration condition. Thereafter, the method continues with determining a target gear based on the vehicle speed offset and the target vehicle speed, and downshifting to the target gear having vehicle speed less than or equal to a vehicle speed corresponding to the current turbine speed. The method ends with maintaining the target gear until a shift delay period is greater than a predetermined delay threshold.

A method for controlling a gear ratio of a continuously variable transmission vehicle includes: a step of detecting a position of a shift lever by a controller; a step of checking, by the controller, a gear ratio variation based on a difference between a desired stage gear ratio and a current gear ratio in a continuously variable transmission when the shift lever is detected to be positioned in a manual range; a step of calculating, by the controller, a gear ratio correction value based on a rate of change of engine RPM when the gear ratio variation is checked as being other than zero after the step of checking the gear ratio variation; and a step of correcting, by the controller, the gear ratio variation in response to the calculated gear ratio correction value after the calculation step.

The present invention is a control device for an automatic transmission, the control device being adapted to control the automatic transmission including a torque converter and a stepped transmission mechanism provided on a power transmission route from the torque converter to drive wheels, wherein while a non-driving range of the automatic transmission is selected, determination on interlock in the stepped transmission mechanism is executed on the basis of deceleration of an output shaft of the stepped transmission mechanism and a change in the torque converter.