Method and apparatus to detect a mode-gear mismatch during steady state operation of an electro-mechanical transmission

Method for operating a powertrain including an electro-mechanical transmission mechanically-operatively coupled to an input member of an internal combustion engine and a pair of electric machines for mechanical power flow to an output member through selective actuation of a plurality of torque-transfer clutches, said electric machines electrically-operatively coupled to an energy storage system for electric power flow therebetween, the method comprising:

• commanding operation of the electro-mechanical transmission in a continuously variable operating range state;
• controlling the internal combustion engine in closed loop engine speed control based upon an optimum engine speed;
• monitoring operation of the transmission;
• affirmatively determining absence of a mode-gear mismatch between the commanded operation of the electro-mechanical transmission and an actual operation of the electro-mechanical transmission by monitoring clutch slippage;
• detecting presence of a mode-gear mismatch between the commanded operation of the electro-mechanical transmission and the actual operation of the electro-mechanical transmission;
• and,
• disabling the closed loop engine speed control upon detecting the presence of a mode-gear mismatch between the commanded operation of the electro-mechanical transmission and the actual operation of the electro-mechanical transmission.

Method for operating a powertrain including an electro-mechanical transmission mechanically-operatively coupled to an input member of an internal combustion engine and a pair of electric machines for mechanical power flow to an output member through selective actuation of a plurality of torque-transfer clutches, said electric machines electrically-operatively coupled to an energy storage system for electric power flow therebetween, the method comprising:

• selectively commanding actuation of a single one of the torque transfer clutches;
• affirmatively determining absence of a mode-gear mismatch between the commanded actuation of the single one of the torque transfer clutches and an actual operating state of the transmission by monitoring clutch slippage;
• detecting presence of a mode-gear mismatch between the commanded actuation of the single one of the torque transfer clutches and the actual operating state of the transmission;
• and,
• modifying operation of the powertrain upon detecting the presence of the mode-gear mismatch between the commanded actuation of the single one of the torque transfer clutches and the actual operating state of the transmission.