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 vehicle includes a transmission having a torque converter, a device configured to generate line pressure, and at least one fluid path connecting the device in fluid communication with the torque converter. A controller is programmed to, responsive to an engine-off time exceeding a threshold and a parameter indicative of departure being present, command the device to generate line pressure so that fluid is supplied to the torque converter. The device may be a transmission pump or an accumulator.

A vehicle having a controller is provided. The controller may be configured to, responsive to identification of a braking event predicted to occur in the future, hydraulically charge an accumulator, and responsive to a pressure of the accumulator exceeding a first threshold, cease charging the accumulator, and satisfy transmission line pressure demand with pressure from the accumulator to begin depleting the accumulator to a before initiation of the braking event.

Disclosed is a hydraulic pressure supply system of a dual clutch transmission for a vehicle in which by independently configuring a low pressure supply route and a high pressure supply route, the hydraulic pressure supply system can enable a low hydraulic pressure that is generated in a hydraulic pump for a low pressure to be supplied to a gear lubrication device and a clutch cooling/lubrication device and enable a low hydraulic pressure that is generated in a hydraulic pump for a high pressure to be supplied to a gear control device and a clutch control device.

Methods and systems for improving operation of a vehicle driveline that includes an engine and an automatic transmission with a torque converter are presented. In one non-limiting example, the engine may be stopped while a vehicle in which the engine operates is rolling. A transmission coupled to the engine may be shifted as the vehicle rolls so that vehicle response may be improved if a driver requests an increase of engine torque.

A parking lock apparatus includes an engaging mechanism, a slider, a hydraulic circuit, and a processor. The engaging mechanism is to prevent a rotation of a rotating body when the engaging mechanism is in a mechanical engagement state. The slider is to switch a state of the engaging mechanism between the mechanical engagement state and a mechanical disengagement state in accordance with a position of the slider. The hydraulic circuit is to change the position of the slider. The processor is configured to increase line pressure in the hydraulic circuit when the engaging mechanism is in the mechanical engagement state.

A vehicle is provided. The vehicle may include a controller. The controller may be configured to, responsive to the vehicle traveling at a constant speed for a predetermined time, hydraulically charge the accumulator, and responsive to a pressure of the accumulator exceeding a first threshold that is defined by a road grade, cease charging the accumulator, and satisfy transmission line pressure demand with the pressure to deplete the accumulator.

A vehicle includes a transmission having a torque converter, a device configured to generate line pressure, and at least one fluid path connecting the device in fluid communication with the torque converter. A controller is programmed to, responsive to an engine-off time exceeding a threshold and a parameter indicative of departure being present, command the device to generate line pressure so that fluid is supplied to the torque converter. The device may be a transmission pump or an accumulator.

A control apparatus for a vehicle that including a drive-force transmitting apparatus and a hydraulic control unit. The drive-force transmitting apparatus defines a drive-force transmitting path through which a drive force is to be transmitted by a continuously-variable transmission mechanism when the drive-force transmitting path is established by engagement of an engagement device. An electromagnetic valve of the hydraulic control unit regulates a hydraulic pressure supplied to the electromagnetic valve via a hydraulic passage, such that the regulated hydraulic pressure is supplied toward the engagement device. An accumulator of the hydraulic control unit is connected to the hydraulic passage, so as to store the hydraulic pressure that flows through the hydraulic passage. The control apparatus calculates, based on a storage state of the hydraulic pressure in the accumulator, an input torque inputted to the continuously-variable transmission mechanism when the engagement device is in a releasing process state.

A power transmission includes a first brake, a pressure regulating valve, an accumulator, an oil temperature sensor, a second electromagnetic valve allowing supply of working oil to a piston, and a power transmission control device. The power transmission control device includes a memory relating and storing a working oil temperature and a permission time configured to allow release of the accumulator, and a receiver unit receiving a starting request. The accumulator is connected such that the working oil, in which the pressure is accumulated, can be supplied to the first brake and the piston. The power transmission control device sets a permission time corresponding to a temperature of the working oil on the basis of the memory. The working oil, in which the pressure is accumulated, is supplied to the first brake only during the permission time when restart information is received, while a vehicle performs idling stop control.