A transmission for a vehicle having a prime mover with an output shaft. The transmission includes an offgoing clutch that is selectively connected to the output shaft, and a controller in communication with the prime mover. The controller includes an offgoing clutch control module that determines an offgoing clutch torque profile at the start of a torque phase in a power downshift that does not exceed a predetermined offgoing clutch energy threshold and a torque request module that limits a rate of input torque into the transmission from the prime mover based upon the determined offgoing clutch torque profile.

The present disclosure relates to a method for controlling a lock-up clutch of an automatic transmission. The method includes: a detecting step of detecting, by a controller, a current signal applied to a solenoid valve of an engaging element when a gear change operation begins; and a first increasing control step of controlling, by the controller, an amount of current that is applied to a solenoid valve of a lock-up clutch during an initial fill time period when it is determined that the current signal is applied to the solenoid valve of the engaging element. In particular, the solenoid valve of the engaging element is used to form a gear stage, and the controller increases the amount of current to a predetermined level for a predetermined period of time.

A method for operating a vehicle drivetrain (1) includes proceeding, in the presence of the demand for activation of the engine start-stop function of the vehicle drivetrain (1) and a simultaneously shut-down drive machine (2), from an operating state of the vehicle drivetrain (1) during which a sailing operating function of the vehicle drivetrain (1) is active, during which the drive machine (2) is decoupled from the drive output (3), during which the positively engaging shift element (F) is open and during which a rotational speed (n_ab) of the drive output (3) is higher than a defined rotational speed at which a rotational speed difference between shift element halves of the positively engaging shift element (F) lies within a rotational speed range within which the positively engaging shift element (F) is transferrable into the closed operating state, and actuating the positively engaging shift element (F) in a closing direction no later than when the defined rotational speed is reached.

In a vehicle including an engine, drive wheels, a power transmission system, and an electronic control unit, during shifting of an automatic transmission, a hydraulic command value of a clutch is set to a higher value as an engine power command value is larger, so that a shift or change of the speed ratio proceeds in an electronic continuously variable transmission and the automatic transmission, in accordance with engine power as a product of the engine speed and engine torque, rather than torque of the engine, etc.

A fast valve actuation system for an automatic vehicle transmission includes a pair of spring-biased shift valves. Solenoids control the application of pressurized hydraulic fluid to the head of each of the shift valves. Each shift valve has at least one port that is coupled to a fluid chamber of a torque transferring mechanism of an automatic transmission. The position of each of the shift valves determines whether its ports are connected with fluid pressure. Fluid passages connect the head of each shift valve to the spring pocket of the other shift valve.

A system for a vehicle includes a desired pressure module, a valve actuation module, a filter module, and a capacity detection module. The desired pressure module selectively generates an increase in a desired pressure of hydraulic fluid for a clutch of an automatic transmission. The valve actuation module actuates a solenoid valve based on the desired pressure. The solenoid valve supplies hydraulic fluid to a regulator valve, and the regulator valve supplies hydraulic fluid to the clutch. The filter module filters an acceleration of a shaft of the automatic transmission to generate a filtered acceleration. The capacity detection module indicates whether the clutch reached torque carrying capacity based on the filtered acceleration.

A vehicle transmission apparatus having a starting engagement friction element, which has friction plates and a hydraulic servo including a piston that is moved according to a supplied oil pressure to press the friction plates, which is controlled to be engaged when a vehicle is started by using at least a driving force of the internal combustion engine, and which transfers creep torque. A control device capable of receiving an accelerator operation amount signal and capable of outputting a command value that controls the oil pressure. The control device executes temporary increase control of temporarily increasing the command value, when the accelerator operation amount signal is turned on from a state where the accelerator operation amount signal is off and the command value is output so that the starting engagement friction element transfers the creep torque.

A vehicle control apparatus includes a learning control portion configured to execute a learning control operation, and to limit a learning value obtained through the learning control operation, by a guard value, and an update control portion configured to obtain a new guard value from an external device, and to update the guard value to the new guard value. The update control portion limits the learning value by the new guard value, prior to execution of the learning control operation, such that the learning value is rewritten, by the update control portion, to a value within a new guard-value range defined by the new guard value in a case in which the learning value is deviated from the new guard-value range, and such that the learning value is kept unchanged by the update control portion in a case in which the learning value is within the new guard-value range.

A method for determining a conveying capacity of a hydraulic pump includes opening a blockable flow cross-section in order to connect a pressure side of the hydraulic pump to an area of the hydraulic system through the flow cross-section after operating the hydraulic pump driven at a defined rotational speed. The flow cross-section is configured with the hydraulic pump such that an entire conveying volume flow provided by the hydraulic pump is guided through the flow cross-section when the flow cross-section is open. The method further includes comparing a change to an operating state of the transmission resulting from opening of the flow cross-section to a reference change to the operating state and determining the conveying capacity of the hydraulic pump as a function of a deviation between the change to the operating state and the reference change to the operating state.

Transmissions, control systems for transmissions, and methods of operating transmissions are disclosed herein. A transmission includes an input shaft, an output shaft, one or more clutches, and a control system. The input shaft is configured to receive rotational power supplied by a drive unit. The output shaft is coupled to the input shaft and configured to provide rotational power supplied to the input shaft to a load. The one or more clutches are coupled between the input shaft and the output shaft to selectively transmit rotational power between the input shaft and the output shaft in one or more operating modes of the transmission. Each of the one or more clutches is selectively engageable in response to one or more fluid pressures applied thereto. The control system is configured to control operation of the one or more clutches to select the one or more operating modes of the transmission.