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 vehicle includes a hydraulic control unit (HCU) having a set of electrically-actuated valves configured to open/close to accumulate a pressurized hydraulic fluid in a hydraulic apply circuit of a first clutch of a transmission; a hydraulic fluid pump mechanically driven by an engine and configured to provide the pressurized hydraulic fluid to the HCU; and a controller configured to: prior to temporarily stopping the engine, control the engine and the HCU such that the pressurized hydraulic fluid accumulates in the hydraulic apply circuit of the first clutch to a desired hydraulic fluid pressure, and upon restarting the engine, control the set of electrically-actuated valves of the HCU to provide the pressurized hydraulic fluid from the hydraulic apply circuit first clutch to a hydraulic apply circuit for a second clutch of the transmission to apply the second clutch and shift the transmission into drive.

A method for operating a drivetrain of a motor vehicle, includes, when the motor vehicle is at a standstill and upon demand for a drive torque of the motor vehicle, increasing power (25p) supplied to a separate electric pump drive (25) such that a pressure chamber whose pressurization effects a complete closure or lock-up of a launch element (3) is fast charged with hydraulic pressure from a pump (24). The method also includes performing a launch process of the motor vehicle with the drive source (1) and with a closed or locked-up launch element (3) and reducing the power (25p) supplied to the separate electric pump drive (25) after fast charging the pressure chamber. A related drive train module is also provided.

A transmission park mechanism is hydraulically actuated. Specifically a controller releases the parking pawl by commanding engagement of particular shift elements at an elevated line pressure. The process of transitioning from Park to a Drive or Reverse condition may involve several sequential steps. To reduce the delay between driver selection of Drive or Reverse and completion of the engagement, it is advantageous to raise the line pressure in response to depression of a brake pedal, prior to movement of the shift lever. To limit the adverse fuel economy impact of increased line pressure, the line pressure is lowered again if the driver does not move the shift lever soon after depressing the brake pedal.

A method for controlling an automatic transmission includes reducing, by a controller, a number of rotation of the engine connected to the automatic transmission to the first number of rotation when a shifting of the automatic transmission is started. The method further includes reducing, by the controller, a line pressure that is a hydraulic pressure of a flow line that operates the automatic transmission when the shifting of the automatic transmission is started.

An electronic control unit starts shift initial oil pressure control after the completion of lockup initial oil pressure control when shift control is performed during the performance of lockup control, the electronic control unit starts shift initial oil pressure control after the completion of lockup initial oil pressure control. Besides, the electronic control unit places priority on the shift control and starts the lockup initial oil pressure control after the completion of the shift initial oil pressure control, when the lockup control is performed during the performance of the shift control. Therefore, the shift initial oil pressure control and the lockup initial oil pressure control are prevented from occurring at the same time when the shift control and the lockup control are performed at the same time.

A control apparatus for a vehicle drive-force transmitting apparatus that includes a gear mechanism and a continuously-variable transmission mechanism including a primary pulley, a secondary pulley, a transfer element that is looped over the primary and secondary pulleys, and an actuator configured to apply, to the primary pulley, a thrust, based on which the transfer element is to be clamped by the primary pulley. The vehicle drive-force transmitting apparatus defines a first drive-force transmitting path for transmitting a drive force through the gear mechanism and a second drive-force transmitting path for transmitting the drive force through the continuously-variable transmission mechanism. The control apparatus is configured, upon vehicle deceleration with the first drive-force transmitting path being established, to set a lower limit value of the above-described thrust, based on a gear ratio of the continuously-variable transmission mechanism and an amount of change of a rotational speed of the primary pulley.

A power transmission device for a hybrid vehicle has a first clutch device (1a) disposed in a drivetrain between an engine (E) and a driving wheel (D). A second clutch device (1b) disposed in a drivetrain extends from a motor (M) to the driving wheel (D). The oil pump (P), connected to the motor (M), supplies oil to a predetermined moving component disposed in the vehicle by using driving power of the motor (M). A transmission (A) is disposed in a drivetrain between the engine (E) and the motor (M) and the driving wheel (D). The transmission adjusts rotation speed of the motor (M). The power transmission device supplying oil by causing the motor (M) to rotate the oil pump (P) at an appropriate rotation speed.

The power train of an electric vehicle includes an electric motor and a gearbox coupling the electric motor to a drive wheel. A controller may be configured to initiate a gear shift in the gearbox, and activate one or both of (a) a torque jog in electric motor, or (b) a burst of a pressurized fluid in an actuator to assist with the gear shift.

A vehicle drive device includes a control portion that is allowed to execute a control mode that controls multiple hydraulic elements to cause a vehicle in a stop state of an engine to start moving. The control mode starts controlling part of the multiple hydraulic elements before the engine is started, by using oil pressure accumulated in an accumulator (S8). The control mode starts controlling the rest of the multiple hydraulic elements by using oil pressure that is provided after the engine is started (S16).