Patent ID: 7324885

Claim:
Method for controlling a mode to mode shift in a multi-mode, electro-mechanical transmission including an input member and an output member, first and second torque transfer devices, at least one motor, first mode operation characterized by simultaneous first torque transfer device applied and second torque transfer device released wherein the transmission input member is mechanically coupled to the transmission output member through a continuously variable ratio, second mode operation characterized by simultaneous first torque transfer device released and second torque transfer device applied wherein the transmission input member is mechanically coupled to the transmission output member through a continuously variable ratio, neutral operation characterized by simultaneous first and second torque transfer devices released wherein the transmission output member is mechanically decoupled from the transmission, and fixed-ratio operation characterized by simultaneous first and second torque transfer devices applied wherein the transmission input member is mechanically coupled to the transmission output member through a fixed ratio, comprising: while in one of the first and second modes, releasing the one of the first and second torque transfer devices that is applied to establish neutral mode operation; controlling slip speed across one of the first and second torque transfer devices to substantially zero; and, applying the one of the first and second torque transfer devices across which slip is being controlled when the slip thereacross is substantially zero.