Patent ID: 7010406

Claim:
Method for reducing the occurrence of shift cycling subsequent to exiting a two-clutch fixed-ratio mode in an electrically variable transmission including an input member and an output member, first and second clutches and first and second modes, said first mode characterized by simultaneous first clutch application and second clutch release, said second mode characterized by simultaneous first clutch release and second clutch application, said two-clutch fixed-ratio mode characterized by simultaneous first and second clutch applications wherein the transmission input member is mechanically coupled to the transmission output member through a fixed ratio, comprising: providing a predetermined desired input member speed; determining a synchronous speed for the input member whereat slip across first and second clutches is substantially zero; incrementing a shift confidence factor as a function of a) the difference between the desired input member speed and the synchronous speed and b) the difference between the rate of change of the desired input member speed and the rate of change of the synchronous speed; and, inhibiting the simultaneous application of said first and second clutches until said shift confidence factor attains a predetermined threshold.