Method for use of hydraulically or electrically controlled solenoids under failed on conditions

1. Method to operate a clutch device in an electro-mechanical transmission mechanically-operatively coupled to an internal combustion engine and at least one electric machine, comprising:

in response to a failure condition detected within a flow control device configured to facilitate flow of hydraulic fluid for operating the clutch device, selectively preventing the flow of hydraulic fluid from entering the flow control device and feeding the clutch device;

initiating synchronization of the clutch device when the clutch device is intended for activation; and

only if the clutch device is synchronized, selectively permitting the flow of hydraulic fluid to enter the flow control device to activate the clutch device.

2. The method of claim 1 wherein the failure condition within the flow control device terminates the ability of the flow control device to controllably prevent the flow of hydraulic fluid from being fed to the clutch device.

3. The method of claim 1 wherein the flow of hydraulic fluid is selectively prevented from entering the flow control device by selectively closing a flow management valve in response to the detected failure condition; and wherein the flow of hydraulic fluid is selectively permitted to enter the flow control device by selectively opening the flow management valve only after the clutch device is synchronized.

4. The method of claim 3 wherein the flow management valve is fluidly coupled to a hydraulic fluid inlet of the flow control device and the clutch device is fluidly coupled to a hydraulic feed line of the flow control device.

5. The method of claim 1 wherein the flow control device is a variable pressure control solenoid.

6. The method of claim 1 wherein initiating synchronization of the clutch device comprises:

monitoring rotational speed of input components of the clutch device and rotational speed of output components of the clutch device; and

controlling the rotational speed of the input components toward the monitored rotational speed of the output components.

7. The method of claim 6 wherein the rotational speed of the input components is controlled utilizing the at least one electric machine.

8. The method of claim 1 wherein the clutch device is synchronized when a relative rotational speed between input components and output components of the clutch device is less than a predetermined rotational speed.

9. The method of claim 1 wherein the clutch device is intended for activation based on a desired operating range state of the transmission requiring application of the clutch device.

10. The method of claim 1 wherein selectively permitting the pressurized flow of hydraulic fluid to enter the flow control device to activate of the clutch device comprises:

feeding the clutch device with the flow of hydraulic fluid through the flow control device, the flow of hydraulic fluid fed to the clutch device providing a clamping force sufficient for locking the clutch device.

11. The method of claim 10 wherein the clutch device remains locked subsequent to the provided clamping force for as long as the flow of hydraulic fluid is permitted to enter the flow control device.

12. The method of claim 10 further comprising:

when the clutch device is no longer intended for activation, selectively preventing the flow of hydraulic fluid from entering the flow control device to deactivate the clutch device.

13. Method to operate a clutch device in an electro-mechanical transmission mechanically-operatively coupled to an internal combustion engine and at least one electric machine, comprising:

detecting a failure condition in a pressure control solenoid configured to facilitate flow of hydraulic fluid for operating the clutch device;

selectively closing a solenoid-controlled flow management valve to prevent the flow of hydraulic fluid from entering the pressure control solenoid and feeding the clutch device;

monitoring a desired operating state of the transmission;

initiating synchronization of the clutch device when the clutch device is intended to be locked based on the desired operating state of the transmission; and

selectively opening the solenoid-controlled flow management valve to permit the flow of hydraulic fluid to enter the pressure control solenoid to lock the clutch device only if the clutch device is synchronized.

14. The method of claim 13 wherein the detected failure condition indicates the pressure control solenoid is stuck in an open state preventing the pressure control solenoid from controllably restricting the flow of hydraulic fluid feeding the clutch device.

15. The method of claim 13 wherein the pressure control solenoid receives the flow of hydraulic fluid from the flow management valve and feeds the flow of hydraulic fluid to the clutch device.

16. The method of claim 13 wherein initiating synchronization of the clutch device when the clutch device is intended to be locked comprises:

monitoring rotational speed of input components of the clutch device and rotational speed of output components of the clutch device; and

controlling the rotational speed of the input components toward the monitored rotational speed of the output components.

17. The method of claim 16 wherein the rotational speed of the input components is controlled utilizing the at least one electric machine.

18. The method of claim 16 wherein the rotational speed of the input components is controlled utilizing the engine.

19. The method of claim 13 wherein selectively opening the solenoid-controlled flow management valve to permit the flow of hydraulic fluid further comprises:

maintaining the clutch device locked for as long as the solenoid-controlled flow management valve remains opened.