Patent ID: 8718887

Claim:
Method to monitor a torque transfer device within an electro-mechanical transmission mechanically-operatively coupled to an internal combustion engine and at least one electric machine, said torque transfer device configured to transfer torque through the electro-mechanical transmission to an output member, comprising: executing in a control module the following steps: monitoring slip speed across the torque transfer device; detecting a slip condition when a magnitude of the monitored slip speed is in a direction in which the torque transfer device has capacity and exceeds a rotational speed threshold; executing a failure detection strategy when the slip condition is detected comprising: comparing the slip speed across the torque transfer device to a slip speed failure threshold; monitoring a magnitude of power loss of the torque transfer device; and even if the slip speed across the torque transfer device does not exceed the slip speed failure threshold for a predetermined period of time, detecting a failure condition in the torque transfer device when the magnitude of power loss over time achieves a predetermined energy threshold.