Disclosed is a method for operating a multi-gear vehicle transmission having a plurality of shifting elements (A, B, C, D, E) for engaging gears of the vehicle transmission. In a neutral gear, in which some of the shifting elements (A, B) are already actuated, a transmission input (1) is decoupled from a transmission output (2) of the vehicle transmission. In a driving gear the transmission input (1) is coupled to the transmission output (2) of the vehicle transmission by closing the shifting elements (A, B, C, D, E) associated with the driving gear, in order to propel the vehicle. With the neutral gear engaged a transmission condition is determined, and if a transmission condition with elevated drag losses exists, then in addition to the shifting elements (A, B) actuated in the neutral gear a shifting element (D) associated with a reversing gear of the vehicle transmission is also closed.

A vehicle comprises an autonomous driving system and a vehicle platform that controls the vehicle in response to a command received from the autonomous driving system. In the vehicle, when a first signalindicates an autonomous mode, the vehicle platform performs a shift change requested through a first command only while the second signal indicates a standstill.

The transmission control unit includes a gear ratio abnormality determination unit and a limp home control unit. The gear ratio abnormality determination unit is configured to determine that a gear ratio is abnormal when, during travelling at a predetermined gear position, a difference between an actual gear ratio, which is calculated based on a transmission input shaft rotation speed and a transmission output shaft rotation speed, and a set gear ratio at the predetermined gear position is equal to or greater than a set value. The limp home control unit is configured to, when the gear ratio abnormality determination unit determines that the gear ratio is abnormal, output a disengagement instruction for disengaging all of the plurality of friction elements, when it is confirmed that a neutral state is shifted to according to the output of the disengagement instruction, determine engagement/disengagement of a specific friction element among the plurality of friction elements based on rotation/stop information of a rotation member of the stepped transmission mechanism, and determine an evacuation gear position based on determination information on the engagement/disengagement of the specific friction element, and shift the gear position to the determined evacuation gear position.

The transmission control unit includes a gear ratio abnormality determination unit and a limp home control unit. The gear ratio abnormality determination unit is configured to determine that a gear ratio is abnormal when, during travelling at a predetermined gear position, a difference between an actual gear ratio, which is calculated based on a transmission input shaft rotation speed and a transmission output shaft rotation speed, and a set gear ratio at the predetermined gear position is equal to or greater than a set value. The limp home control unit is configured to, when the gear ratio abnormality determination unit determines that the gear ratio is abnormal, output a disengagement instruction for disengaging all of the plurality of friction elements, when it is confirmed that a neutral state is shifted to according to the output of the disengagement instruction, determine engagement/disengagement of a specific friction element among the plurality of friction elements based on rotation/stop information of a rotation member of the stepped transmission mechanism, and determine an evacuation gear position based on determination information on the engagement/disengagement of the specific friction element, and shift the gear position to the determined evacuation gear position.

A transmission is subject to thermal management to prevent damage or failure due to overheating. Sensors can be employed to capture characteristics of a transmission, such as fluid temperature or pressure. Further, a predictive model can be invoked to predict characteristics based on current and future conditions. Characteristics can be compared with a threshold for intervention. A thermal mitigation strategy can be generated and initiated when characteristics satisfy the threshold. The thermal mitigation strategy can specify various actions to dissipate heat, including altering shift control logic and triggering mechanical devices that can increase airflow, reduce air temperature, or both surrounding the transmission.

A transmission is subject to thermal management to prevent damage or failure due to overheating. Sensors can be employed to capture characteristics of a transmission, such as fluid temperature or pressure. Further, a predictive model can be invoked to predict characteristics based on current and future conditions. Characteristics can be compared with a threshold for intervention. A thermal mitigation strategy can be generated and initiated when characteristics satisfy the threshold. The thermal mitigation strategy can specify various actions to dissipate heat, including altering shift control logic and triggering mechanical devices that can increase airflow, reduce air temperature, or both surrounding the transmission.

A method of controlling a transmission of a vehicle, includes determining, by a controller, whether a shift prohibition condition for preventing overheating of the transmission of the vehicle in a terrain mode, which is a rough road driving mode of the vehicle, is satisfied; determining, by the controller, whether a shift operation of the transmission corresponding to a busy shift phenomenon of the transmission is detected when the shift prohibition condition is satisfied; and prohibiting, by the controller, shifting of the transmission when the shift operation of the transmission corresponding to the busy shift phenomenon of the transmission is detected.

A method of controlling a transmission of a vehicle, includes determining, by a controller, whether a shift prohibition condition for preventing overheating of the transmission of the vehicle in a terrain mode, which is a rough road driving mode of the vehicle, is satisfied; determining, by the controller, whether a shift operation of the transmission corresponding to a busy shift phenomenon of the transmission is detected when the shift prohibition condition is satisfied; and prohibiting, by the controller, shifting of the transmission when the shift operation of the transmission corresponding to the busy shift phenomenon of the transmission is detected.

A vehicle gear-shifting control apparatus is equipped with an engine, a motor, an automatic transmission, a friction brake system, and a controller which executes, during deceleration of a vehicle during which the friction brake system is distributing a braking force to front and rear wheels, a regeneration control of imparting a regenerative braking torque to the rear wheels by causing the motor to perform a regeneration operation and a gear-shifting control of changing a shift stage of the automatic transmission by outputting a gear-shifting signal in accordance with the rotation speed of an input shaft to the automatic transmission. When the controller determines an oversteered state of the vehicle during the regeneration control, the controller increases an input torque of the input shaft so that the regenerative braking torque decreases while maintaining the regeneration operation of the motor and, at the same time, limits the gear-shifting control.

A vehicle gear-shifting control apparatus is equipped with an engine, a motor, an automatic transmission, a friction brake system, and a controller which executes, during deceleration of a vehicle during which the friction brake system is distributing a braking force to front and rear wheels, a regeneration control of imparting a regenerative braking torque to the rear wheels by causing the motor to perform a regeneration operation and a gear-shifting control of changing a shift stage of the automatic transmission by outputting a gear-shifting signal in accordance with the rotation speed of an input shaft to the automatic transmission. When the controller determines an oversteered state of the vehicle during the regeneration control, the controller increases an input torque of the input shaft so that the regenerative braking torque decreases while maintaining the regeneration operation of the motor and, at the same time, limits the gear-shifting control.