In order to estimate the degree of fatigue in a power transmission system and suitably manage a durability life, this durability life management device of the power transmission system is provided with: an input section which receives an input of vehicle running information including a torque generated by a driving source; a control section which controls the degree of damage to a component of the power transmission system on the basis of the running information and determines, on the basis of the degree of damage, whether the degree of fatigue in the power transmission system is high; and an output section which outputs a signal indicating that the degree of fatigue is high, when the degree of fatigue is determined to be high.

An electronic control module (ECM) may obtain sensor information concerning an engine and may determine, based on the sensor information, a speed of the engine. The ECM may cause a swashplate of a hydraulic pump to adjust based on the speed of the engine.

An electronic control module (ECM) may obtain sensor information concerning an engine and may determine, based on the sensor information, a speed of the engine. The ECM may cause a swashplate of a hydraulic pump to adjust based on the speed of the engine.

A method for operating a vehicle drive train (1) includes, during a downshift, disengaging at least one shift element (A through F) from a power flow of the transmission (5), guiding a power transmission capacity of a torque converter lockup clutch (4) to a level at which the torque converter lockup clutch (4) is in a non-slip operating condition during a positive engine override when a rotational speed of a prime mover (2) is guided towards a synchronous speed of a demanded desired ratio, and guiding the power transmission capacity of the torque converter lockup clutch (4)no later than a point in time of the downshift at which the rotational speed of the prime mover (2) is equal to the synchronous speed of the desired ratioto a level at which the torque converter lockup clutch (4) is transferred into a continuous slip operation due to torque.

A method for operating a vehicle drive train (1) includes, during a downshift, disengaging at least one shift element (A through F) from a power flow of the transmission (5), guiding a power transmission capacity of a torque converter lockup clutch (4) to a level at which the torque converter lockup clutch (4) is in a non-slip operating condition during a positive engine override when a rotational speed of a prime mover (2) is guided towards a synchronous speed of a demanded desired ratio, and guiding the power transmission capacity of the torque converter lockup clutch (4)no later than a point in time of the downshift at which the rotational speed of the prime mover (2) is equal to the synchronous speed of the desired ratioto a level at which the torque converter lockup clutch (4) is transferred into a continuous slip operation due to torque.

A vehicle control device performing upshift to a forward gear stage in a current travel section in a case where: (1) the forward gear stage is higher than a current gear stage; (2) a travel resistance of a vehicle in the current travel section is greater than a driving force in a case of traveling at the forward gear stage; (3) a stall amount until the vehicle passes an end point of the current travel section in a case where the vehicle travels in the current travel section at the forward gear stage is equal to or smaller than a specified value; and (4) a value obtained by subtracting the travel resistance of the vehicle in a forward travel section from a driving force in a case where the vehicle travels in the forward travel section at the forward gear stage is equal to or greater than a predetermined value.

A vehicle control device performing upshift to a forward gear stage in a current travel section in a case where: (1) the forward gear stage is higher than a current gear stage; (2) a travel resistance of a vehicle in the current travel section is greater than a driving force in a case of traveling at the forward gear stage; (3) a stall amount until the vehicle passes an end point of the current travel section in a case where the vehicle travels in the current travel section at the forward gear stage is equal to or smaller than a specified value; and (4) a value obtained by subtracting the travel resistance of the vehicle in a forward travel section from a driving force in a case where the vehicle travels in the forward travel section at the forward gear stage is equal to or greater than a predetermined value.

A shift by wire-based transmission system and a method for controlling the same, may include a transmission lever, a main controller that determines a target gear stage and a current control delay time of an actuator based on a manipulation signal received from the transmission lever and controls driving of the actuator based on the determined target gear stage and the current control delay time to determine a gear stage position in a response to the driving of the actuator, and a transmission control unit that controls a hydraulic pressure based on the gear stage position determined by the main controller.

A shift control device includes: a stepless shift controller executing a stepless shift mode and controlling a transmission gear ratio of a continuously variable transmission in a stepless fashion; a stepped shift controller executing a stepped shift mode and controlling the continuously variable transmission using fixed transmission gear ratios; a mode setting unit switching the shift mode to the stepped shift mode when a vehicle is to be accelerated; and a transmission-gear-ratio setting unit setting an initial transmission gear ratio in the stepped shift mode when the shift mode is to be switched to the stepped shift mode. The transmission-gear-ratio setting unit estimates a variation in an engine rotation speed when the shift mode is to be switched to the stepped shift mode, and sets a fixed transmission gear ratio, at which the variation is greater than or equal to a lower limit value, as the initial transmission gear ratio.

A shift control device includes: a stepless shift controller executing a stepless shift mode and controlling a transmission gear ratio of a continuously variable transmission in a stepless fashion; a stepped shift controller executing a stepped shift mode and controlling the continuously variable transmission using fixed transmission gear ratios; a mode setting unit switching the shift mode to the stepped shift mode when a vehicle is to be accelerated; and a transmission-gear-ratio setting unit setting an initial transmission gear ratio in the stepped shift mode when the shift mode is to be switched to the stepped shift mode. The transmission-gear-ratio setting unit estimates a variation in an engine rotation speed when the shift mode is to be switched to the stepped shift mode, and sets a fixed transmission gear ratio, at which the variation is greater than or equal to a lower limit value, as the initial transmission gear ratio.