CONTROL ARRANGEMENT FOR A VARIABLE PULLEY TRANSMISSION

摘要

CONTROL ARRANGEMENT FOR A VARIABLE PULLEY TRANSMISSION : A continuously variable transmission (CVT) with adjustable width pulleys has its belt tension and ratio controlled by an electronic-hydraulic system. The CVT also has a fluid-cooled clutch on the output pulley shaft. The engine speed, transmission output speed, throttle position, and gearshift position are sensed, and signals representing this information are passed to a computer. The computer provides set point signals denoting desired engine speed, line pressure, and clutch cooling condition to a control system. An electromechanical valve (408) assembly regulates fluid flow to the CVT primary sheave (30), to control CVT ratio as a function of the computer provided set engine speed signal. A further electromechanical valve (414) assembly controls the line pressure in the hydraulic system, which is applied to the secondary pulley (36) to maintain belt tension, as a function of the set pressure signal provided by the computer. A solenoid-operated valve (420), regulated by the control system (406), either returns waste fluid from the second valve assembly directly to sump, or passes the fluid to the clutch when cooling is indicated.