Patent ID: 8062001

Claim:
A method of hydraulic pressure control for a hybrid transmission having a main pump deriving power from an internal combustion engine and in selective fluid flow communication with a hydraulic circuit of the hybrid transmission through a main regulator, and an auxiliary pump not deriving power from the internal combustion engine and in selective fluid flow communication with the hydraulic circuit through an auxiliary regulator, the method comprising: commanding the internal combustion engine to begin transition to an engine-off state, and commanding the main pump to begin a transition to a non-operating state; moving a pressure control solenoid (PCS) from a low position of the PCS to a high position of the PCS, wherein the PCS is operatively in communication with both the main regulator and the auxiliary regulator, such that the main regulator moves from a low pressure setting to a high pressure setting and the auxiliary regulator moves from a low pressure setting to a high pressure setting; commanding the auxiliary pump to begin a transition to an auxiliary-on state; operating the PCS in the high position during the transition of the main pump to the non-operating state; and finishing the transition of the auxiliary pump to the auxiliary-on state before finishing the transition of the main pump to the non-operating state.