| Abstract |
An automatic transmission lubrication control system includes a modulating, spring biased spool valve and feedback circuit. One end of the spoof valve is supplied with line pressure hydraulic fluid. The valve spool modulates a flow of lubricating hydraulic fluid from the cooler and its position is determined by a force balance between the line pressure, the regulated fluid output pressure to the lubrication system and the force of the biasing spring. In a reduced lubrication state, a signal from a transmission control module opens a solenoid valve to provide high pressure fluid to a three way check valve which closes the feedback circuit and applies high pressure fluid to the opposite end• of the valve spool. This action moves the valve spool to a travel limit, closing off flow from the cooler. Hydraulic fluid from the torque converter feed is then routed to the lubrication system. |