US Patent 7677373 Lock-up clutch control method

A torque converter lock-up clutch may be controlled by a lock-up clutch regulator control valve. The valve is utilized to selectively direct a fluid to the torque converter or to a pressure regulator valve. For example, in a hydrodynamic condition of the torque converter, the valve permits fluid to flow to the torque converter. In a lock-up condition of the torque converter, the valve directs fluid to a pressure regulator valve which selectively permits pressure to build in the torque converter.