Abstract: A hybrid powertrain includes a control unit that regulates electric power interchange an energy storage device and a motor/generator for causing selective torque generation by the motor/generator and for controlling engagement of torque-transmitting mechanisms. The control unit is configured to place the torque-transmitting mechanism in slipping engagement to launch the vehicle and thereby decouple a fixed relationship between engine torque and motor/generator torque or between engine torque and torque at the output member. A method of operating a hybrid vehicle powertrain is also provided.

Abstract: A single range, electrically variable transmission (EVT) is provided with a lockup clutch that reduces motor power requirements. When applied, the lockup clutch allows engine torque to be transmitted directly to the output without the necessity of a motor/generator supplying reaction torque. With the lockup clutch applied, the transmission operates with zero electro-mechanical power flow at a fixed mechanical ratio, thus mitigating the power peak which occurs through the motor/generators. Input-split, output-split, and compound-split transmissions are disclosed. A method of operating an EVT with a lockup clutch is also provided.

Abstract: A hybrid powertrain includes an electrically variable transmission and an internal combustion engine. The transmission is operable to provide a continuously variable mode of operation. The engine is capable of variable displacement in that at least half of the cylinders contained therein are deactivatable. Additionally the internal combustion engine operates with a late intake valve closing strategy to increase the peak efficiency of the internal combustion engine.

Abstract: A method for controlling the cranking of an engine of a vehicle powertrain system having a rechargeable energy storage system that is adapted to provide electric power to an electric machine, wherein the system is adapted to exit from the engine crank state as a function of an output voltage of the energy storage system to the electric machine during the crank state, if the output voltage is less than a crank undervoltage threshold for a predetermined crank time. According to the method, the crank undervoltage threshold is a function of the number of failed start attempts, generally decreasing as a function of the number of failed start attempts. The predetermined crank time is a function of a magnitude of a difference between the output voltage and the crank undervoltage threshold.

Abstract: A hybrid powertrain incorporates an engine, two motor/generator mechanisms, and a planetary gearset. The planetary gearset has at least one torque-transmitting mechanism, which may be selectively energized to provide a brake on one of the motor/generators thereby reducing the electrical power generation within the hybrid transmission.

Abstract: A method and apparatus to control acceleration of a vehicle equipped with an electrically variable transmission and including a regenerative braking system, each are operably connected to a vehicle driveline. The method and apparatus include determining which one of a preselected shift selector position for the transmission is commanded, and determining operator demand for acceleration, using inputs from throttle pedal and brake pedal. Vehicle acceleration is measured, and magnitude of commanded torque transferred from the electrically variable transmission and the regenerative braking system to the vehicle driveline is controlled based upon the commanded preselected shift selector position, the operator demand for acceleration, and the measured vehicle acceleration.

Abstract: A two-mode, compound-split, electro-mechanical transmission utilizes an input member for receiving power from an engine, and an output member for delivering power from the transmission. First and second motor/generators are operatively connected to an energy storage device through a control for interchanging electrical power among the storage device, the first motor/generator and the second motor/generator. The transmission employs three planetary gear sets. Each planetary gear arrangement utilizes first, second and third gear members. At least one of the gear members in the first or second planetary gear sets is connected to the first motor/generator. Another gear member in the second and third planetary gear arrangement is connected to the second motor/generator. One of the gear members of the first or second planetary gear sets is continuously connected to one of the gear members in the third planetary gear set.