Abstract: A method and system for operating a vehicle that includes a driveline disconnect clutch and a step-ratio transmission is described. In one example, the method includes shifting the step-ratio transmission to neutral and accelerating an engine to an expected input shaft speed of the step-ratio transmission via applying full output capacity of an electric machine to the engine.

Abstract: A method for downshifting a vehicle having an automatic transmission is described. In one example, the method determines whether or not conditions are met for a power matching downshift. If conditions are met for a power matching downshift, output power of a powertrain propulsion torque source at an end of the power matching downshift is adjusted to an output power of the powertrain propulsion torque source at the beginning of the power matching downshift plus an offset power.

Abstract: A method for downshifting a vehicle having an automatic transmission is described. In one example, the method determines whether or not conditions are met for a power matching downshift. If conditions are met for a power matching downshift, output power of a powertrain propulsion torque source at an end of the power matching downshift is adjusted to an output power of the powertrain propulsion torque source at the beginning of the power matching downshift plus an offset power.

Abstract: Systems and methods for operating a vehicle that includes an engine and an electric machine are described. In one example, an actual total number of transmission gear downshifts are counted to determine whether or not a transmission clutch characterization is immature. The transmission clutch characterization may be adjusted if it is determined to be immature.

Abstract: A vehicle includes a torque converter bypass clutch, a wheel, a generator, and a controller. The torque converter bypass clutch is disposed between the wheel and the electric machine. The controller is programmed to, responsive to slip of the clutch exceeding a threshold during regenerative braking, energize the electric machine such that a torque being transferred from the wheel to the electric machine increases at a first rate and increase clutch pressure to decrease the slip. The controller is further programmed to, responsive to the slip decreasing to less than the threshold during the regenerative braking, adjust electric machine energization such the that torque being transferred from the wheel to the electric machine increases at a second rate that is greater than the first rate.

Abstract: A method and system for operating a vehicle that includes a driveline disconnect clutch and a step-ratio transmission is described. In one example, the method includes shifting the step-ratio transmission to neutral and accelerating an engine to an expected input shaft speed of the step-ratio transmission via applying full output capacity of an electric machine to the engine.

Abstract: Systems and methods for operating a hybrid powertrain or driveline that includes an engine and an integrated starter/generator are described. In one example, the integrated starter/generator may rotate a torque converter during a vehicle activation process if a vehicle soak time exceeds a threshold. The integrated starter/generator may not rotate the torque converter during a vehicle activation process if a vehicle soak time is less than the threshold.

Abstract: Systems and methods for operating a vehicle that includes an engine and an electric machine are described. In one example, an actual total number of transmission gear downshifts are counted to determine whether or not a transmission clutch characterization is immature. The transmission clutch characterization may be adjusted if it is determined to be immature.

Abstract: A vehicle includes a torque converter bypass clutch, a wheel, a generator, and a controller. The torque converter bypass clutch is disposed between the wheel and the electric machine. The controller is programmed to, responsive to slip of the clutch exceeding a threshold during regenerative braking, energize the electric machine such that a torque being transferred from the wheel to the electric machine increases at a first rate and increase clutch pressure to decrease the slip. The controller is further programmed to, responsive to the slip decreasing to less than the threshold during the regenerative braking, adjust electric machine energization such the that torque being transferred from the wheel to the electric machine increases at a second rate that is greater than the first rate.

Abstract: Systems and methods for operating a hybrid powertrain or driveline that includes an engine and an integrated starter/generator are described. In one example, the integrated starter/generator may rotate a torque converter during a vehicle activation process if a vehicle soak time exceeds a threshold. The integrated starter/generator may not rotate the torque converter during a vehicle activation process if a vehicle soak time is less than the threshold.

Abstract: While a transmission range selector is in a Park position, a controller engages multiple transmission shift elements to place the transmission in a tie-up state. In the tie-up state, both the transmission output shaft and the turbine shaft are held against rotation by the shift elements. To transition from Park to Drive, the controller releases one of the shift elements to place the transmission in a 1st gear state. To transition from Park to Reverse, the controller releases a different one of the shift elements to place the transmission in a reverse state. The controller may wait until the driver releases the brake pedal to release the shift element.

Abstract: 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.

Abstract: In a transmission hydraulic control system, a gain control valve may be used to switch between a low gain and a high gain based on line pressure. Line pressure may be controlled as a function of turbine torque. If the gain of a holding element or oncoming element changes during a shift as a result of changing turbine torque, shift quality may degrade. If the gain is set low at the beginning of the shift, the controller limits engine torque to ensure that the line pressure is not increased beyond a level that would cause a gain switch. If the gain is set high at the beginning of a shift, the controller maintains the line pressure high enough to prevent a switch to low gain, even if turbine torque drops.

Abstract: 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.

Abstract: A controller commands an engine torque level in response to a driver demanded torque based on an accelerator pedal position. If the driver demanded torque decreases rapidly during or just prior to a torque phase of a shift, the controller commands the engine to temporarily generate torque exceeding the driver demand. The controller sets a nominal engine torque equal to the driver demand torque before the rapid decrease, slowly decreases the nominal engine torque during the torque phase, and decreases the nominal torque at progressively faster rates during the inertia phase to bring the nominal torque back into agreement with the driver demanded torque. The commanded engine torque is based on the nominal torque, but may be less than the nominal torque during the inertia phase to permit the engine speed to decrease faster.

Abstract: While a transmission range selector is in a Park position, a controller engages multiple transmission shift elements to place the transmission in a tie-up state. In the tie-up state, both the transmission output shaft and the turbine shaft are held against rotation by the shift elements. To transition from Park to Drive, the controller releases one of the shift elements to place the transmission in a 1st gear state. To transition from Park to Reverse, the controller releases a different one of the shift elements to place the transmission in a reverse state. The controller may wait until the driver releases the brake pedal to release the shift element.

Abstract: A vehicle powertrain includes an engine and a transmission, each controlled by controllers that communicate with one another. When the vehicle is coasting in certain gears, a one-way clutch over-runs. When the driver depresses the accelerator pedal (tips in), the transmission controller adjusts a transmission torque demand limit which is communicated to the engine controller. In response, the engine controller adjusts the engine torque, resulting in a smooth re-engagement of the one-way clutch.

Abstract: While a transmission range selector is in a Park position, a controller engages multiple transmission shift elements to place the transmission in a tie-up state. In the tie-up state, both the transmission output shaft and the turbine shaft are held against rotation by the shift elements. To transition from Park to Drive, the controller releases one of the shift elements to place the transmission in a 1st gear state. To transition from Park to Reverse, the controller releases a different one of the shift elements to place the transmission in a reverse state. The controller may wait until the driver releases the brake pedal to release the shift element.

Abstract: A vehicle powertrain includes an engine and a transmission, each controlled by controllers that communicate with one another. When the vehicle is coasting in certain gears, a one-way clutch over-runs. When the driver depresses the accelerator pedal (tips in), the transmission controller adjusts a transmission torque demand limit which is communicated to the engine controller. In response, the engine controller adjusts the engine torque, resulting in a smooth re-engagement of the one-way clutch.

Abstract: In a transmission hydraulic control system, a gain control valve may be used to switch between a low gain and a high gain based on line pressure. Line pressure may be controlled as a function of turbine torque. If the gain of a holding element or oncoming element changes during a shift as a result of changing turbine torque, shift quality may degrade. If the gain is set low at the beginning of the shift, the controller limits engine torque to ensure that the line pressure is not increased beyond a level that would cause a gain switch. If the gain is set high at the beginning of a shift, the controller maintains the line pressure high enough to prevent a switch to low gain, even if turbine torque drops.