Method to control a hybrid transmission using on-off switches controlling hydraulic flow to a clutch

1. A control module-implemented method to control a transmission through a shift event, the transmission comprising a plurality of synchronously operated clutches selectably transmitting torque from a torque generative device to an output member, the method comprising:

executing in the control module the following steps:

monitoring a desired shift event comprising monitoring a clutch to be engaged;

determining a time at which the clutch to be engaged will be synchronized;

determining a required clutch fill time for the clutch to be engaged; and

actuating a binary on-off hydraulic control switch to commence providing pressurized hydraulic fluid to the clutch to be engaged at the beginning of the clutch fill time and based upon coordinating the time at which the clutch to be engaged will be synchronized simultaneously with the end of the required clutch fill time, wherein a pressure within the clutch to be engaged transitions the clutch to be engaged into a touching state wherein the clutch is filled when the binary on-off switch is actuated;

operating the clutch to be engaged in a synchronized state until the pressure within the clutch to be engaged is sufficient to allow for a clutch torque capacity which exceeds a minimum required clutch torque capacity; and

permitting torque to be transferred through the clutch when clutch torque capacity exceeds the minimum required clutch torque capacity.

2. The method of claim 1 , further comprising:

subsequent to synchronization of the clutch to be engaged, iteratively determining a clutch torque capacity for the clutch to be engaged;

comparing the clutch torque capacity to a minimum required clutch torque capacity; and

utilizing the clutch to be engaged to transfer torque based upon the comparing.

3. The method of claim 1 , wherein the required clutch fill time is determined according to a computational model of the clutch.

4. The method of claim 1 , wherein the required clutch fill time is determined by referencing a look-up table.

5. The method of claim 1 , wherein the binary on-off hydraulic control switch is hydraulically actuated.

6. The method of claim 1 , wherein the binary on-off hydraulic control switch comprises an electromechanical solenoid.

7. The method of claim 1 , wherein the binary on-off hydraulic control switch comprises a servo motor.

8. The method of claim 1 , wherein actuating the binary on-off hydraulic control switch comprises actuating the on-off hydraulic control switch such that the clutch to be engaged will be synchronized before the clutch to be engaged is filled.

9. The method of claim 1 , further comprising:

during the desired shift event, maintaining a drive torque to the output member by transmitting torque through a second clutch.

10. The method of claim 9 , further comprising providing the drive torque with an engine; and

wherein synchronization of the clutch to be engaged is effected with torque from an electric machine.

11. A control module-implemented method to control a transmission through a shift event, the transmission comprising a plurality of synchronously operated clutches selectably transmitting torque from a torque generative device to an output member, the method comprising:

executing in the control module the following steps:

monitoring a desired shift event comprising:

identifying a clutch to be engaged in the desired shift event; and

monitoring a time at which the clutch to be engaged will be synchronized;

determining through a computational model of the clutch a required clutch fill time for the clutch to be engaged;

actuating a binary on-off hydraulic control switch to commence providing pressurized hydraulic fluid to the clutch to be engaged at the beginning of the clutch fill time and-coordinating the time at which the clutch to be engaged will be synchronized simultaneously with the end of the required clutch fill time, wherein pressure within the clutch to be engaged transitions the clutch to be engaged into a touching state wherein the clutch is filled when the binary on-off hydraulic control solenoid is actuated;

maintaining the binary on-off hydraulic control switch in an actuated state;

iteratively determining a clutch torque capacity for the clutch to be engaged;

operating the clutch to be engaged in a synchronized state until the clutch torque capacity exceeds a minimum required clutch torque capacity.

12. Apparatus to control a transmission through a shift event, the transmission comprising a plurality of synchronously operated clutches selectably transmitting torque from a torque generative device to an output member, the apparatus comprising:

a selected one of the plurality of clutches to be engaged during the shift event;

a hydraulically actuated binary on-off hydraulic control switch controlling a flow of pressurized hydraulic fluid to the selected clutch; and

a control module configured to:

monitor a desired shift event comprising monitoring the selected clutch,

determine a time at which the selected clutch will be synchronized,

determine a required clutch fill time for the selected clutch, and

actuate the binary on-off hydraulic control switch at the beginning of the clutch fill time and coordinating the time at which the selected clutch will be synchronized with the end of the required clutch fill time, wherein pressure within the clutch to be engaged transitions the clutch to be engaged into a touching state wherein the clutch is filled when the binary on-off hydraulic control switch is activated;

operate the selected clutch in a synchronized state until the pressure within the selected clutch is sufficient to allow for a clutch torque capacity which exceeds a minimum required clutch torque capacity; and

permit torque to be transferred through the selected clutch when the clutch torque capacity exceeds the minimum required clutch torque capacity.