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

1. Method for operating a vehicular powertrain including an electro-mechanical transmission mechanically-operatively coupled to an internal combustion engine, said electro-mechanical transmission selectively operative in one of a plurality of continuously variable and fixed gear operating range states, the method comprising:

commanding operation of the electro-mechanical transmission in one of the continuously variable operating range states;

commanding operation of the engine in a closed-loop speed control mode, the closed-loop speed control mode always comprises operation of the engine;

monitoring operator inputs;

monitoring a transmission output shaft speed measured by a transmission output speed sensor; and

terminating operation of the engine in the closed-loop speed control mode when a time-rate change in the transmission output shaft speed exceeds a threshold absent a change in the monitored operator inputs.

2. The method of claim 1 wherein the monitored transmission output comprises a rotational speed of an output shaft of the transmission rotatably connected to a driveline and the threshold corresponds to a vehicular acceleration rate of about three meters per second per second.

3. The method of claim 2 , wherein the time-rate change in rotational speed of the output shaft and the threshold comprise absolute values.

4. Method for operating a vehicular powertrain including an electro-mechanical transmission mechanically-operatively coupled to an internal combustion engine, the method comprising:

monitoring operator inputs;

monitoring a transmission output; and

terminating an engine operating mode when a time-rate change in the transmission output exceeds a threshold absent a change in the monitored operator inputs;

wherein monitoring operator inputs comprises monitoring an operator brake input, and a change in the monitored operator inputs comprises an operator command for braking.

5. Method to control operation of a powertrain comprising an engine mechanically-operatively coupled to an electro-mechanical transmission selectively operative in one of a fixed gear and a continuously variable operating range state, comprising:

operating the transmission in the continuously variable operating range state;

operating the engine in a closed-loop speed control mode, the closed-loop speed control mode always comprises operation of the engine;

monitoring operator inputs;

monitoring a transmission output shaft speed measured by a transmission output speed sensor; and

terminating engine operation in the closed-loop speed control mode when a time-rate change in the transmission output shaft speed exceeds a threshold absent a corresponding change in the monitored operator inputs.