Method for transitioning control in a multi-mode hybrid transmission

Method for operating a hybrid transmission including first and second torque machines, first and second selectable one-way clutches, an input member and an output member, the hybrid transmission operative in a first continuously variable mode by applying the first selectable one-way clutch and operative in a second continuously variable mode by applying the second selectable one-way clutch, the method comprising:

• controlling input torque and motor torques of the first and second torque machines using a first kinematic relationship to achieve a preferred output torque in the first continuously variable mode wherein the first selectable one-way clutch is applied in a fully closed state;
• commanding a transition from operating in the first continuously variable mode to operating in the second continuously variable mode, comprising:
• transitioning the first selectable one-way clutch to a first one-way state to transfer torque in a first direction,
• controlling rotational direction of the first torque machine in a first direction and adjusting rotational speed of the first torque machine toward a predetermined nominally negative rotational speed,
• applying the second selectable one-way clutch in a second one-way state to transfer torque in a second direction opposite the first direction, and controlling rotational direction of the first torque machine in the first direction and adjusting rotational speed of the first torque machine toward a synchronous speed, and
• controlling input torque and motor torques of the first and second torque machines using a second kinematic relationship to achieve a preferred output torque when the rotational speed of the first torque machine is substantially equal to zero revolutions per minute;
• and then
• operating the hybrid transmission in the second continuously variable mode.

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 torque transfer clutches including a first clutch and a selectable one-way clutch, the method comprising:

• operating the hybrid transmission in an initial continuously variable mode including applying the first clutch and including 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 selectable one-way clutch and including 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 to transition the first clutch to a deactivated state, transition the selectable one-way clutch to the applied state, and transition from 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 clutch elements of the first clutch and the selectable one-way clutch are substantially synchronized, wherein executing the multi-step process comprises:
• deactivating the first clutch;
• controlling rotational speed of the first torque machine in a first direction;
• applying the 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 synchronized 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 including applying the selectable one-way clutch in a fully-closed state.