Patent ID: 8262537

Claim:
Method for operating a multi-mode hybrid transmission configured to transfer power between an input member and an output member and first and second torque machines in one of two continuously variable modes by selectively applying two selectable one-way clutches, the method comprising: operating the hybrid transmission in an initial continuously variable mode including applying the first selectable one-way clutch and controlling an input torque at the input member and motor torques of the first and second torque machines using a first kinematic relationship to achieve a preferred output torque; commanding the hybrid transmission to transition to operating in a target continuously variable mode including applying the second selectable one-way clutch and controlling the input torque at the input member and motor torques of the first and second torque machines using a second kinematic relationship to achieve the preferred output torque; and executing a multi-step process including transitioning the first selectable one-way clutch to a deactivated state, transitioning the second selectable one-way clutch to the applied state, and transitioning controlling the input torque at the input member and the motor torques of the first and second torque machines using the first kinematic relationship to using the second kinematic relationship to achieve the preferred output torque when rotational speeds of the first and second torque machines are substantially a synchronous speed, wherein executing the multi-step process comprises: applying the first selectable one-way clutch in a one-way state; controlling rotational speed of the first torque machine in a first direction; applying the second selectable one-way clutch in a one-way state when the rotational speed of the first torque machine approaches a predetermined nominally negative speed less than the synchronous speed; controlling rotational direction of the first torque machine in the first direction and adjusting rotational speed of the first torque machine toward the synchronous speed; controlling rotational direction of the first torque machine in a second direction opposite the first direction; and operating the hybrid transmission in the target continuously variable mode to generate and transfer torque to the output member.