Patent attributes
A line-to-lube pressure regulator valve assembly for an automatic transmission including an internal check valve that opens in the Park gear range and at low engine speeds to feed line pressure to the torque converter in response to a substantially lower hydraulic fluid pressure than is required to open the pressure regulator valve in its factory specified operating range. As engine speed increases and sufficient hydraulic fluid pressure is built up within the torque converter charge circuit, the present internal check valve is again closed and the pressure regulator valve assembly opens as it would normally to feed line pressure to the torque converter directly. When the engine is shut off, the present internal check valve is biased to a closed position preventing transmission fluid from draining back through the valve to the transmission sump thereby eliminating the converter drain back problem.
