Abstract: A system and method for controlling a transmission gear shift during a braking event in a vehicle having an electric motor and friction brakes both operable to brake the vehicle includes the step of reducing friction braking to increase wheel torque during the braking event. The braking event includes both friction braking and regenerative braking. The reduction in friction braking to increase the wheel torque is based at least in part on a reduction in the wheel torque resulting from a change in gear ratio of a step-ratio transmission during the transmission gear shift.

Abstract: A vehicle includes an electric machine, a starter-generator, and a controller. The electric machine is coupled to a traction battery via an inverter. The starter-generator is mechanically coupled with an engine and electrically coupled with a low-voltage battery. And, the controller charges the low-voltage battery with power from the traction battery, and in response to a torque demand of the electric machine falling below a threshold defined by losses of the inverter, transitions to the starter-generator to charge the low-voltage battery.

Abstract: A system and method for controlling a hybrid vehicle having an engine selectively coupled by an upstream clutch to an electric machine, which is selectively coupled by a downstream clutch to a step-ratio transmission, include at least one controller programmed to control the engine and the electric machine in response to entering a lash zone in anticipation of a wheel torque reversal to adjust a gain applied to an active motor damping torque controller to reduce driveline oscillations and backlash.

Abstract: Systems and methods for operating a hybrid powertrain that includes an engine and a motor/generator are described. The systems and methods adjust battery charging and discharging as well as engine and motor torque based on whether or not the vehicle is operating in a cruise control mode. In one example, curves that provide a basis for operating an engine and motor based on driver demand torque are compressed during a vehicle cruise control mode to improve powertrain efficiency.

Abstract: A hybrid vehicle control system and method include a controller programmed to, while a transmission is in PARK or NEUTRAL, start an engine, close a disconnect clutch selectively coupling the engine to an electric machine, and control the electric machine to charge a traction battery in response to the accelerator pedal position exceeding an idle position and being less than a threshold. The controller controls transmission impeller speed in response to accelerator pedal position exceeding the threshold to allow revving the engine in response to accelerator pedal. A method for controlling a hybrid vehicle includes starting an engine, closing a clutch between the engine and an electric machine, and controlling the engine and the electric machine to either: i) charge a traction battery or ii) rev the engine based on accelerator pedal position relative to a threshold above an idle position while the transmission is in PARK or NEUTRAL.

Abstract: A vehicle includes an engine having a crankshaft, a transmission, an electric machine, and at least one controller. The transmission includes a torque converter having a turbine fixed to a turbine shaft that is driveably connected to driven wheels of the vehicle. The torque converter includes an impeller and a bypass clutch configured to selectively lock the impeller and the turbine relative to each other. The electric machine includes a rotor selectively coupled to the crankshaft via a disconnect clutch and fixed to the impeller. The at least one controller is configured to generate a first torque command for the electric machine that defines a magnitude equal to driver-demanded torque while the bypass clutch is locked. The controller is further configured to, in response to a reduction in fluid pressure supplied to the bypass clutch, generate a second torque command for the electric machine that defines a magnitude equal to driver-demanded torque plus impeller inertia torque.

Abstract: A control system is provided to account for differences in engine response times and motor response times during an upshift in a transmission. A vehicle includes a driveline that has an engine, a traction motor, and a transmission selectively connected in series. A control area network (CAN) connects a plurality of controllers. At least one of the controllers is programmed to, during an upshift in the transmission, output signals over the CAN to reduce torque of the traction motor. The controller also reduces the engine torque based on signal delays in the CAN.

Abstract: A vehicle includes a motor positioned between an engine and a driveline connected to a vehicle wheel, and a controller. The controller controls engine torque and maintains motor torque during wheel torque and driveline component torque reversals to limit a vehicle output torque rate of change through a lash region associated with a range of driveline torque ratios. A method of controlling a hybrid vehicle includes controlling engine torque to a specified profile and maintaining motor torque at a generally constant value during at least one of wheel torque and driveline component torque reversals to limit a vehicle output torque rate of change through a lash region associated with a range of driveline torque ratios.

Abstract: A vehicle includes an engine, electric machine, starter-generator, and a controller. The engine and electric machine are each configured to propel the vehicle. The starter-generator is coupled to the engine and is configured to adjust engine speed during an engine start-up event. The controller is programmed to, in response to engine speed increasing towards a target speed during an engine start-up event, generate a target drag torque with the starter-generator to reduce overshoot of the target engine speed.

Abstract: A system and method for controlling a vehicle powertrain including an engine and a motor operable to propel the vehicle includes reducing a torque of the motor at a first torque reduction rate from a torque level above a minimum motor torque in response to a deceleration request. A torque of the engine is reduced at a second torque reduction rate less than the first torque reduction rate in response to the deceleration request.

Abstract: A hybrid electric vehicle includes an engine and an electric machine, both capable of providing propulsion power. A clutch is configured to selectively couple the engine to the electric machine. At times, the vehicle may be subject to excessive loads, such as a large amount of weight in the vehicle or the vehicle towing another object. At least one controller is programmed to engage the clutch and start the engine in response to a load of the vehicle exceeding a predetermined threshold and a release of the brake pedal while the vehicle is stopped and in drive. This increases available engine torque prior to vehicle launch in anticipation of an upcoming acceleration demand.

Abstract: A hybrid electric vehicle includes an engine and an electric machine, both capable of providing torque to transmission gearing. A clutch is disposed between the engine and the electric machine and is configured to selectively couple the engine to the electric machine. At times in which control of the amount of engine torque transmitted to the gearing is desirable, a controller is programmed to slip the clutch. If the controller is able to determine the amount of torque transmitted through the slipping clutch, the controller alters an output of the electric machine based upon the torque through the clutch. If, however, the controller is unable to determine the amount of torque transmitted through the slipping clutch, the controller alters the output of the electric machine based upon an acceleration of the electric machine.

Abstract: A vehicle includes a starter motor, an engine having an output mechanically coupled to the starter motor, a transmission having an input, and an electric machine mechanically coupled to the transmission input. The vehicle further includes a clutch configured to mechanically couple the electric machine and the output of the engine, and at least one controller. The at least one controller is programmed to initiate an engine start based on driver demand. The controller is further configured to enable pressure to the clutch for the engine start if driver demand is less than a calibratable torque value or enable the starter motor for the engine start if the driver demand is greater than a calibratable torque value. The controller may lock the clutch to the output of the engine in response to the speed of the engine being approximately equal to the speed of the electric machine.

Abstract: A vehicle includes a motor positioned between an engine and a driveline connected to a vehicle wheel, and a controller. The controller controls engine torque and maintains motor torque during wheel torque and driveline component torque reversals to limit a vehicle output torque rate of change through a lash region associated with a range of driveline torque ratios. A method of controlling a hybrid vehicle includes controlling engine torque to a specified profile and maintaining motor torque at a generally constant value during at least one of wheel torque and driveline component torque reversals to limit a vehicle output torque rate of change through a lash region associated with a range of driveline torque ratios.

Abstract: Systems and methods for operating a transmission of a hybrid powertrain that includes a motor/generator are described. The systems and methods may classify transmission degradation in response to an estimated transmission input shaft speed that is determined from transmission output shaft speed. In one example, transmission degradation may be correctable transmission degradation, partial transmission degradation, and continuous transmission degradation.

Abstract: Systems and methods for improving operation of a driveline disconnect clutch for a hybrid vehicle shifting are presented. In one example, pressure of a working fluid supplied to the driveline disconnect clutch is adjusted in response to a rate of change in accelerator pedal position. Further, pressure of the working fluid may be decreased responsive to selected operating conditions.

Abstract: A method for operating a driveline of a vehicle includes adjusting operation of an electric machine to provide a torque difference between a driver demand torque and an engine output torque, when the electric machine is not operating in an operating range in which electric machine efficiency is less than a threshold efficiency. The operating range has a first, positive torque limit defining a positive extent of the operating range and a second, negative torque limit defining a negative extent of the operating range. In response to the torque difference being within the operating range and greater than zero, the torque output of the electric machine is maintained at the first torque limit, whereas in response to the torque difference being within the operating range and less than zero, the torque output of the electric machine is maintained at the second torque limit.

Abstract: Systems and methods for operating a transmission of a hybrid powertrain that includes a motor/generator are described. The systems and methods may improve engine starting during engine starts where little or larger driver demand torques are requested. In one example, engine torque may be commanded to a torque based on a filtered driver demand torque, the filtered driver demand torque filtered based on a position of an accelerator pedal.

Abstract: Methods and systems are provided for improving engine restart operations occurring during a transmission shift in a hybrid vehicle. Engine speed is controller during cranking and run-up to approach a transmission input shaft speed that is based on the future gear of the transmission shift. Engine speed is controlled via adjustments to spark, throttle, and/or fuel, to expedite engine speed reaching the synchronous speed.

Abstract: A control strategy is provided for a hybrid vehicle that will increase drivability during low or decreasing driver demands. Coordination between shifting the transmission and stopping or (non-demand) starting of the engine can increase drivability. The vehicle includes a motor/generator with one side selectively coupled to the engine and another side selectively coupled to the transmission. The control strategy acts when an engine start or stop is requested while driver demand is decreasing and a shift of the transmission is demanded. To inhibit these events from proceeding simultaneously, the control strategy delays the engine from starting or stopping until the transmission has finished shifting, or vice versa.