Transmission and Hydraulic Control System

A hydraulic control system for an automatic transmission with a torque converter includes two regulator valves controlled by a single variable force solenoid (VFS). A bypass clutch regulator valve increases the pressure to a bypass clutch apply chamber as the VFS pressure increases. A converter charge regulator valve decreases the pressure in a converter charge circuit as the VFS pressure increases. The converter charge circuit is in series with a lubrication circuit. An orifice restricts the flow through these circuits such that they can be supplied from the line pressure circuit rather than a lower priority circuit. In one embodiment, an on/off solenoid opens a flow control valve to bypass the orifice when additional flow is required. In another embodiment, an electric pump supplements the flow in these circuits when required. This later embodiment includes a switch valve such that the electric pump also supports stop/start operation.