The present document relates to a driveline for a vehicle, the driveline comprising a hydrodynamic retarder, a first driveline component such as a transmission input, and a controller configured to activate the hydrodynamic retarder at a point in time which is determined based on a rotational acceleration of the first driveline component. The present document further relates to a method of controlling a hydrodynamic retarder.

A compression-based speed limiting for a driveline including a transmission is described herein. The driveline controller detects over speeding and controls the ratio of the transmission to therefore increase compression of the prime mover and therefore limit speed.

A compression-based speed limiting for a driveline including a transmission is described herein. The driveline controller detects over speeding and controls the ratio of the transmission to therefore increase compression of the prime mover and therefore limit speed.

A control device of a gear transmission-equipped vehicle includes a power controller that starts power reduction control when it is determined that a start condition is satisfied, the power reduction control being control of reducing power transmitted from a driving source to a gear transmission. The start condition includes: a condition that a detection value of a gear position sensor that detects a current gear position of the gear transmission falls within a transition region between engagement regions corresponding to respective gear positions; and a condition that a speed difference obtained by subtracting a rotational speed of an output shaft of the gear transmission from a rotational speed of an input shaft of the gear transmission is a threshold or more.

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 hydraulic pressure calculation apparatus is applied to a gear shifting system including a transmission configured to switch between a connected state and a disconnected state of a friction engagement element depending on a hydraulic pressure supplied from a hydraulic circuit, and a hydraulic controller configured to control the hydraulic circuit. The hydraulic pressure calculation apparatus includes a memory and a processor. The memory stores pieces of mapping data of a plurality of phases obtained by dividing a period from a start to an end of switching between the connected state and the disconnected state of the friction engagement element. Each piece of the mapping data defines a mapping. The processor is configured to output, as an output variable, an estimated hydraulic pressure variable indicating an estimated value of an actual hydraulic pressure supplied from the hydraulic circuit to the friction engagement element.

A hydraulic pressure calculation apparatus is applied to a gear shifting system including a transmission configured to switch between a connected state and a disconnected state of a friction engagement element depending on a hydraulic pressure supplied from a hydraulic circuit, and a hydraulic controller configured to control the hydraulic circuit. The hydraulic pressure calculation apparatus includes a memory and a processor. The memory stores pieces of mapping data of a plurality of phases obtained by dividing a period from a start to an end of switching between the connected state and the disconnected state of the friction engagement element. Each piece of the mapping data defines a mapping. The processor is configured to output, as an output variable, an estimated hydraulic pressure variable indicating an estimated value of an actual hydraulic pressure supplied from the hydraulic circuit to the friction engagement element.

A nonlinear closed-loop control combined with an integral time-delay feedback control is disclosed to adjust a speed ratio of an infinitely variable transmission (IVT) system. A speed ratio control for an IVT system involves a forward speed controller and a crank length controller for different speed ranges. The time-delay control is designed to reduce speed fluctuations of the output speed of an IVT with an accurate speed ratio. The speed ratio of an IVT with the disclosed control strategy can achieve an excellent tracking response for the desired constant output speed and reduce speed fluctuations of the output speed of an IVT by the time-delay feedback control.

A nonlinear closed-loop control combined with an integral time-delay feedback control is disclosed to adjust a speed ratio of an infinitely variable transmission (IVT) system. A speed ratio control for an IVT system involves a forward speed controller and a crank length controller for different speed ranges. The time-delay control is designed to reduce speed fluctuations of the output speed of an IVT with an accurate speed ratio. The speed ratio of an IVT with the disclosed control strategy can achieve an excellent tracking response for the desired constant output speed and reduce speed fluctuations of the output speed of an IVT by the time-delay feedback control.

The present invention provides a shift control method implemented in a vehicle equipped with an automatic transmission for controlling an input shaft rotation speed to a target input shaft rotation speed during a shift. The method includes setting of a basic target synchronization rotation speed that is a basic target value of the input shaft rotation speed during the shift, and setting of a corrected target input shaft rotation speed as the target input shaft rotation speed when the shift is a downshift without a requirement for a driving force of the vehicle, The corrected target input shaft rotation speed is obtained by decreasingly correcting the basic target synchronization rotation speed. Further, a decreasing correction amount of the basic target synchronization rotation speed is set so as to become larger as a deceleration of the vehicle becomes larger.