SLIP RESTRICTING DEVICE OF V-BELT TYPE CONTINUOUSLY VARIABLE TRANSMISSION FOR PREVENTING SLIP OF V-BELT TO PULLEY IN DOWNSHIFTING BY LOWERING PRIMARY PULLEY PRESSURE

摘要

PURPOSE: A slip restricting device of a V-belt type continuously variable transmission is provided to prevent lowering of fuel efficiency and slip of the belt by estimating slip between the V-belt and the pulley and restricting decrease of the primary pulley pressure. CONSTITUTION: A slip restricting device of a V-belt type continuously variable transmission comprises a belt slip estimating unit estimating slip between the V-belt and the pulley in lowering primary pulley pressure, and a primary pulley pressure decrease forbidding unit restricting decrease of primary pulley pressure in detecting slip between the V-belt and the pulley. Slip between the V-belt and the pulley is estimated in case of primary pulley rpm to be below 900 rpm and primary pulley pressure to be below 0.2 MPa during downshifting by lowering primary pulley pressure. Actual speed ratio before the predetermined time is set to be the target speed ratio at the moment for estimating the belt slip, and downshifting is forbidden by moving up the step motor. Thus, upshifting is performed, and the slip of the belt is restricted by increasing primary pulley pressure.