The statements in this section merely provide background information related to the present disclosure. Accordingly, such statements are not intended to constitute an admission of prior art.
Powertrain systems including hybrid powertrain systems and extended-range electric powertrain systems are configured to operate in a plurality of operating modes. Such powertrain systems use torque generators, clutches and transmissions to generate and transfer torque to a driveline. Known torque generators include internal combustion engines and electric motor/generators. Known hybrid powertrain systems and extended-range electric powertrain systems include an internal combustion engine coupled via an input member to a hybrid transmission employing one or more torque machines, e.g., electric motor/generators. Torque management on known hybrid powertrain systems and extended-range electric powertrain systems includes balancing torque outputs of the internal combustion engine and the torque machines to transfer torque to an output member of a hybrid transmission in response to an operator torque request.
Known non-hybrid powertrain systems employ a torque converter between an internal combustion engine and an automatic transmission to manage torque transfer therebetween. Known hybrid powertrain systems and extended-range electric powertrain systems may include an activatable clutch element configured to couple and decouple an internal combustion engine and an input member of a hybrid transmission system. Known hybrid transmission systems manage load across locked clutches primarily through the management of torque output of the torque machines. Clutch load is managed by forcing a powertrain system to operate in such a way as to off-load torque across a target clutch during its deactivation. When torque output of the torque machines is insufficient to fully manage clutch load, i.e., offload torque from an off-going clutch due to motor capacity and/or battery limitations, engine torque may be used to fill in the gap.