Air ingestion into a transmission hydraulic system may lead to a number of issues. For example, the time to engage a hydraulically actuated parking mechanism may be excessive. As another example, the pump may not prime properly on a subsequent engine start. The air ingestion issue may be detected based on variability of transmission line pressure. When the line pressure variability exceeds a threshold, actions are taken to mitigate the potential issues.

A transmission includes an input shaft coupled to a prime mover, a countershaft, main shaft, and an output shaft, with gears between the countershaft and the main shaft. A shift actuator selectively couples the input shaft to the main shaft by rotatably coupling gears between the countershaft and the main shaft. The shift actuator is mounted on an exterior wall of a housing including the countershaft and the main shaft. An integrated actuator housing includes a single external power access for the shift actuator. A controller interprets controls the shift actuator with actuating and opposing pulses, and interprets a shaft displacement angle, determines if the transmission is in an imminent zero or zero torque region, and performs a transmission operation in response to the transmission in the imminent zero or zero torque region.

A controller of a power transmission system for a vehicle includes an electronic control unit. When a difference between a secondary pressure set by use of a command pressure of the electromagnetic control valve for the secondary pulley, and an actual pressure obtained by a hydraulic pressure sensor, is larger than a predetermined pressure difference, the electronic control sets a primary pressure and the secondary pressure such that a speed ratio of a continuously variable transmission becomes substantially equal to a maximum value. The electronic control unit determines that there is an abnormality that an output pressure of the electromagnetic control valve for a secondary pulley is low, when the speed ratio is smaller than a predetermined first determination value, and determines that there is an abnormality in the hydraulic pressure sensor, when the speed ratio is larger than a predetermined second determination value.

A CVT is provided with a primary pulley (1) and a secondary pulley (2) between which a belt (3) is wound, and hydraulic pressure control valves (5, 6, 7) which control pulley hydraulic pressures. A CVT controller (8) sets a base current indicated value to be output to solenoids (5a, 6a, 7a) of the hydraulic pressure control valves (5, 6, 7), on the basis of a pulley hydraulic pressure indicated value. A dither control unit (58) of the CVT controller (8) superimposes a dither current onto the base current indicated value to be output to the solenoids (5a, 6a, 7a) if, during pulley hydraulic pressure control, the situation is determined, on the basis of belt slip determination information, to be such that belt slipping is highly likely to occur.

An electro-hydraulic control system for a multispeed transmission having a plurality of torque-transmitting mechanisms includes a controller for operably controlling the transmission, a fluid source for supplying hydraulic fluid, and a plurality of torque-transmitting mechanisms being operably selected between an applied and an unapplied state to achieve a plurality of ranges including at least one reverse, a neutral, and a plurality of forward ranges. The system includes a plurality of trim systems having pressure control solenoids and trim valves. The system may also include one or more shift valves disposed in fluid communication with the fluid source and being capable of moving between stroked and de-stroked positions. In any given range, only two of the plurality of torque-transmitting mechanisms may be applied. Moreover, three of the plurality of pressure control solenoids are normally high solenoids, and the remaining solenoids are normally low solenoids.

A transmission includes an accumulator to hold one of more shift elements in an engaged state while an engine is off. The transmission also includes a hydraulic park system that disengages park in response to engagement of two shift elements. In some circumstance, draining the accumulator in an uncontrolled manner in the presence of a failed valve may lead to unintentionally disengaging park. To avoid this, the accumulator is discharged in a controlled manner. Fluid is first transferred from the accumulator to a shift element apply chamber. Then, the fluid is vented from the shift element apply chamber.

A transmission assembly including a clutch system, an accumulator, and a controller is provided. The clutch system may include a flow source. The accumulator may be selectively in communication with the flow source via a solenoid valve. The controller may be programmed to, responsive to detection of a vehicle stop and the accumulator charged below a predetermined threshold, output a command to open the solenoid valve to rapidly charge the accumulator from the flow source. The predetermined threshold may be an accumulator pressure between 700 kPa and 900 kPa. The controller may be further programmed to, responsive to detection of the accumulator being charged to or above the predetermined threshold, output a shut down command to an engine in communication with the transmission assembly and to output a close command to the solenoid valve. The flow source may be a pump out circuit or a line pressure circuit.

While automatic driving control is being performed, traveling in a driving state of a vehicle corresponding to an unconverged region (including an unperformed region and a performed region) is preferentially selected between the traveling in the driving state of the vehicle corresponding to the unconverged region, and traveling in the driving state of the vehicle corresponding to a converged region. As such, learning control that corrects an amount of operation associated with control of the vehicle is performed more easily throughout the entire learning regions regardless of a usage state of the vehicle by a driver. Therefore, it is possible to achieve an appropriate traveling state at an early stage by the learning control that corrects the amount of operation associated with control of the vehicle.

A transmission includes an input shaft coupled to a prime mover, a countershaft, main shaft, and an output shaft, with gears between the countershaft and the main shaft. A shift actuator selectively couples the input shaft to the main shaft by rotatably coupling gears between the countershaft and the main shaft. The shift actuator is mounted on an exterior wall of a housing including the countershaft and the main shaft. An integrated actuator housing includes a single external power access for the shift actuator. A controller interprets a shaft displacement angle, determines if the transmission is in an imminent zero or zero torque region, and performs a transmission operation in response to the transmission in the imminent zero or zero torque region.

A vehicle control device for a vehicle with a drive source and an automatic transmission including a friction engaging element for transmitting a driving force of the drive source to drive wheels by being engaged by a hydraulic pressure, wherein the vehicle control device is configured to perform an abnormality diagnosis of a solenoid valve for adjusting a hydraulic pressure to be supplied to the friction engaging element on the basis of a slip amount of the friction engaging element, and prohibit the abnormality diagnosis of the solenoid valve if a hydraulic pressure upstream of the solenoid valve is below a predetermined hydraulic pressure at which the friction engaging element is engaged, the hydraulic pressure upstream of the solenoid being a source hydraulic pressure to be adjusted by the solenoid valve.