Method and apparatus to monitor rotational speeds in an electro-mechanical transmission

A method for controlling operation of a powertrain comprising an electro-mechanical transmission mechanically-operatively coupled to an internal combustion engine and first and second electric machines to transmit mechanical power to an output member, the method comprising:

• monitoring input speeds of the engine and the first and second electric machines;
• monitoring operations of the internal combustion engine and the first and second electric machines;
• determining input speeds and changes in input speeds for the internal combustion engine and the first and second electric machines;
• comparing the input speeds to threshold input speeds;
• comparing the changes in input speeds to threshold changes in input speeds;
• and
• substantially immediately reducing power outputs of the internal combustion engine and the first and second electric machines to zero power when any one of the input speeds and the changes in input speeds exceeds the corresponding threshold.

A method for controlling a powertrain comprising an electro-mechanical transmission mechanically-operatively coupled to an internal combustion engine and first and second electric machines to selectively transmit mechanical power to an output, the method comprising:

• monitoring operator inputs;
• monitoring operation of the internal combustion engine and the first and second electric machines;
• determining input speeds, changes in input speeds, and input torques for the internal combustion engine and the first and second electric machines to the transmission;
• comparing the input speeds to threshold input speeds;
• comparing the changes in input speeds to threshold changes in input speeds;
• comparing the input torques to threshold input torques;
• ramping down the input torques of the internal combustion engine and the first and second electric machines at varying ramp rates when any one of the input speeds, changes in input speeds, and input torques exceeds the corresponding threshold;
• and
• discontinuing the ramping down of the input torques from the internal combustion engine and the first and second electric machines when the input speeds are substantially less than the threshold input speeds.