A gear-position learning device for an automatic clutch transmission includes a transmission configured to be shifted by an operation of a driver of a vehicle, a clutch device disposed in a transmission path between the transmission and an engine and configured to be connected and disconnected by actuation of a clutch actuator, a controller configured to control connection and disconnection of the clutch device performed by the clutch actuator, a shift drum configured to rotate according to a shift operation that the driver performs on a shift operator and switch the shift stage of the transmission, and a rotational position defining mechanism configured to define a rotational position of the shift drum, wherein the controller has a learning mode for learning a rotation angle of the shift drum and is configured to control connection and disconnection of the clutch device during the learning mode such that the shift drum is at a rotational position determined by the rotational position defining mechanism.

A rotational system can include a shaft assembly rotationally coupling a first rotor, a second rotor, and a fluid pump. A fluid circuit can include the fluid pump that can be configured to motivate a working fluid through the fluid circuit. A pressurizing valve can be disposed downstream of the fluid pump wherein the rotational system can be configured to rotationally decouple the first rotor from the second rotor by closing the pressurizing valve. The pressurizing valve can be actuated by a controller. A method can include raising a pressure differential across a fluid pump driven by a shaft assembly thereby applying an increased braking torque to the shaft assembly. The pressure differential can be raised by actuating a valve in hydraulic communication with the fluid pump. The shaft assembly can rotationally couple a first rotor with a second rotor, and increasing the braking torque can decouple the rotors.

A method for operating a dual-clutch transmission with two clutches. During realization of a ratio, a first clutch is closed and a second clutch is open. During a ratio change, the first clutch is opened and the second clutch is closed. During a ratio change within short operating times, a target actuating pressure of the clutch for engagement is set to a fast-charging pressure level and subsequently adjusted to a closing pressure level, while a target actuating pressure of the clutch for disengagement is adjusted to an opening pressure level before setting the closing pressure level of the clutch for engagement. At least during a ratio change, an actual actuating pressure of the clutch for engagement is monitored and the target actuating pressure of the clutch for disengagement is adjusted to the opening pressure level if the actual actuating pressure of the clutch for engagement exceeds a pressure threshold.

Systems and methods for selecting and scheduling which of a plurality of engine starting devices starts an internal combustion engine of a hybrid vehicle are presented. In one example, a scheduled start of the internal combustion engine via a driveline disconnect clutch is withdrawn during conditions when both a transmission gear shift is requested or in process and when a driver urgency level is greater than a threshold level.

A power take-off (PTO) drive assembly for a transmission includes a shaft defining a shaft axis, a PTO gear defined radially about the shaft axis, and a clutch assembly positioned between the shaft and the PTO gear and having an engaged position and a disengaged position. When the clutch assembly is in the engaged position, torque is transferred from the shaft to the PTO gear. When the clutch assembly is in the disengaged position, torque is not transferred from the shaft to the PTO gear.

A vehicle propulsion system that includes a prime mover having an output shaft, a torque converter including a compressor coupled to the output shaft of the prime mover, a turbine fluidly coupled to the compressor, and a torque converter clutch for selectively mechanically coupling the compressor to the turbine, a continuously variable transmission (CVT) coupled to the turbine of the torque converter, and a controller that is programmed to receive signals indicating operating conditions of the vehicle propulsion system, determine whether the received signals indicate a reduction in ratio in the CVT is impending, determine whether to open the torque converter clutch based upon a determination that a reduction in ratio is impending, and open the torque converter clutch in response to a determination to open the torque converter clutch.

A method of controlling an automatic transmission is provided. The automatic transmission includes a piston having first and second surfaces opposite from each other, friction plates, engaging and disengaging hydraulic pressure chambers for supplying and discharging hydraulic pressure and directing the piston to push the friction plates to be engaged and disengaged, a hydraulic pressure control valve for supplying and discharging hydraulic pressure to and from the chambers, first and second oil paths communicating the valve with the chambers, and a pressure reducing valve disposed in the second oil path and for preventing hydraulic pressure of the disengaging hydraulic pressure chamber from exceeding a given set pressure. The second surface has a larger area for receiving hydraulic pressure than an area of the first surface for receiving hydraulic pressure. The method includes changing the given set pressure according to information regarding a state of the automatic transmission.

A clutch control method is used in a vehicle that has a dog clutch and an engagement sensor, which detects an engagement of a dog clutch. The clutch control method includes executing an engagement of the dog clutch when a magnitude of a differential rotation of the dog clutch is less than or equal to a prescribed value when the engagement sensor is normal and then determining the engagement of the dog clutch using the engagement sensor. The clutch control method further includes setting the differential rotation of the dog clutch to a value larger than the prescribed value when the engagement sensor has failed and then determining the engagement of the dog clutch based on a difference between the differential rotation of the dog clutch at a time of starting the engagement of the dog clutch and the differential rotation of the dog clutch.

A system for controlling transmission shifting includes a controller that receives a shift request signal and determines if a clutch has been unapplied for more than a predetermined time. With a yes determination, a maximum fill time value for hydraulic fluid to be applied to a clutch control circuit is determined, the maximum fill time value being a function of time the clutch has been unapplied and temperature. A signal indicative of an amount of engine RPM flare after the transmission executes the requested shift is received and a modified maximum fill time value is determined as a function of this flare. The modified maximum fill time value is stored as a replacement for the maximum fill time value for use with a subsequent transmission shifts using this clutch, and reduces an amount of air in the control circuit and an amount of flare with subsequent transmission shifts.

A method is disclosed for reducing chatter vibrations of a friction clutch controlled automatically by a clutch actuator on the basis of a target clutch torque (M(s)) assigned to a clutch torque which is to be transmitted. The friction clutch is positioned in a drivetrain between an internal combustion engine and a transmission, having a present actual clutch torque which is marked by vibrations as a result of vibrations (M(i)). From a transmission behavior of the present actual clutch torque (M(i)), an absolute amplitude and a phase of an input signal detected at the output of the friction clutch and conveyed to a regulator are ascertained, and a phase-selective disturbance torque is ascertained. From the phase-selective disturbance torque, a phase-correct correction torque (M(k)) is determined, and the target clutch torque (M(s)) is corrected by the regulator. The correction torque (M(k)) is weighted with a specifiable intensification factor.