Transmission clutch closed loop slip controller and method

Abstract

A continuously variable belt-driven transmission includes a hydraulic torque converter, a variable diameter displaceable input pulley, a variable diameter displaceable output pulley, forward and reverse planetary gearing, a differential mechanism and half shafts driven from the differential mechanism. A slipping lockup clutch is hydraulically actuated to connect and disconnect selectively the impeller and turbine of the torque converter. The radial position of the drive belt that engages the input and output pulleys is determined by selectively pressurizing and venting a cylinder to move displaceable sheaves of a pulley. Hydraulically actuated clutches are selectively engageable to produce forward drive or reverse drive from the output pulley to the differential mechanism. Various sensors produce electric signals as input to a microprocessor indicate the position of the engine throttle, the magnitude of engine speed, primary pulley speed, secondary pulley speed, converter lockup clutch pressure, belt load pressure, line pressure and the position of a PRNDL gear selector. A valve body hydraulically actuates, in accordance with the output produced by the computer, the forward clutch, the reverse clutch, the torque converter lockup clutch and the displaceable sheaves of the input pulley and output pulley. An electronic feedback system controls the slip, engagement and disengagement of the torque converter lockup clutch.

Dependencies are inferred from the claim text.